From 3454aba504af8e23a9021cda963fa1f822436e6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-S=C3=A9bastien?= <git@jscaux.org>
Date: Tue, 8 Feb 2022 17:21:33 +0100
Subject: [PATCH] Update 2022-02-08 17:21

---
 build/a.html                 |  10 +++-
 build/a_l.html               |  10 +++-
 build/c.html                 |  10 +++-
 build/c_m.html               |  10 +++-
 build/c_m_cs.html            |  10 +++-
 build/c_m_cs_cyl.html        | 106 +++++++++++++----------------------
 build/c_m_cs_hyp.html        |  10 +++-
 build/c_m_cs_sph.html        |  70 +++++++++--------------
 build/c_m_dc.html            |  10 +++-
 build/c_m_dc_curl.html       |  10 +++-
 build/c_m_dc_d2.html         |  40 +++++++------
 build/c_m_dc_del.html        |  10 +++-
 build/c_m_dc_div.html        |  10 +++-
 build/c_m_dc_g.html          |  10 +++-
 build/c_m_dc_pr.html         |  10 +++-
 build/c_m_dd.html            |  10 +++-
 build/c_m_dd_1d.html         |  10 +++-
 build/c_m_dd_3d.html         |  50 +++++++----------
 build/c_m_dd_div.html        |  24 ++++----
 build/c_m_ic.html            |  10 +++-
 build/c_m_ic_ftc.html        |  10 +++-
 build/c_m_ic_ftg.html        |  10 +++-
 build/c_m_ic_gauss.html      |  10 +++-
 build/c_m_ic_ip.html         |  10 +++-
 build/c_m_ic_lsv.html        |  28 +++++----
 build/c_m_ic_stokes.html     |  14 +++--
 build/c_m_uf.html            |  10 +++-
 build/c_m_uf_cyl.html        |  10 +++-
 build/c_m_uf_sph.html        |  10 +++-
 build/c_m_uf_vi.html         |  10 +++-
 build/c_m_va.html            |  10 +++-
 build/c_m_va_cp.html         |  10 +++-
 build/c_m_va_n.html          |  10 +++-
 build/c_m_va_pds.html        |  10 +++-
 build/c_m_va_sp.html         |  10 +++-
 build/c_m_va_tp.html         |  10 +++-
 build/c_m_vf.html            |  10 +++-
 build/c_m_vf_helm.html       |  10 +++-
 build/c_m_vf_pot.html        |  16 +++---
 build/d.html                 |  14 +++--
 build/d_emd.html             |  10 +++-
 build/d_emd_ce.html          |  10 +++-
 build/d_emd_emw.html         |  10 +++-
 build/d_emf.html             |  10 +++-
 build/d_ems.html             |  10 +++-
 build/d_ems_ca.html          |  10 +++-
 build/d_ems_ms.html          |  10 +++-
 build/d_emsm.html            |  10 +++-
 build/d_emsm_msm.html        |  10 +++-
 build/d_m.html               |  10 +++-
 build/d_red.html             |  10 +++-
 build/emd.html               |  18 +++---
 build/emd_Fl.html            |  10 +++-
 build/emd_Fl_Fl.html         |  16 ++++--
 build/emd_Fl_e.html          |  14 +++--
 build/emd_Fl_i.html          |  16 ++++--
 build/emd_Fl_ief.html        |  16 ++++--
 build/emd_Me.html            |  10 +++-
 build/emd_Me_Me.html         |  16 ++++--
 build/emd_Me_dc.html         |  14 +++--
 build/emd_Me_ebM.html        |  10 +++-
 build/emd_Me_mc.html         |  10 +++-
 build/emd_ce.html            |  18 +++---
 build/emd_ce_amom.html       |  12 ++--
 build/emd_ce_ce.html         |  12 ++--
 build/emd_ce_mom.html        |  14 +++--
 build/emd_ce_mst.html        |  16 ++++--
 build/emd_ce_poy.html        |  22 +++++---
 build/emd_emw.html           |  18 +++---
 build/emd_emw_ep.html        |  14 +++--
 build/emd_emw_mpw.html       |  12 ++--
 build/emd_emw_we.html        |  12 ++--
 build/emdm.html              |  10 +++-
 build/emdm_Me.html           |  10 +++-
 build/emdm_Me_Mem.html       |  26 +++++----
 build/emdm_Me_bc.html        |  12 ++--
 build/emdm_emwm.html         |  10 +++-
 build/emdm_emwm_ad.html      |  10 +++-
 build/emdm_emwm_ad_c.html    |  10 +++-
 build/emdm_emwm_plm.html     |  12 ++--
 build/emdm_emwm_refl.html    |  10 +++-
 build/emdm_emwm_refl_Ba.html |  10 +++-
 build/emdm_emwm_refl_Fe.html |  10 +++-
 build/emdm_emwm_refl_ni.html |  10 +++-
 build/emdm_emwm_refl_oi.html |  18 +++---
 build/emdm_emwm_refr.html    |  10 +++-
 build/emdm_emwm_wg.html      |  10 +++-
 build/emdm_emwm_wg_c.html    |  10 +++-
 build/emdm_emwm_wg_gw.html   |  10 +++-
 build/emdm_emwm_wg_r.html    |  10 +++-
 build/emf.html               |  18 +++---
 build/emf_g.html             |  10 +++-
 build/emf_g_Cg.html          |  10 +++-
 build/emf_g_Lg.html          |  14 +++--
 build/emf_svp.html           |  18 +++---
 build/ems.html               |  10 +++-
 build/ems_ca.html            |  18 +++---
 build/ems_ca_fe.html         |  18 +++---
 build/ems_ca_fe_L.html       |  12 ++--
 build/ems_ca_fe_g.html       |  14 +++--
 build/ems_ca_fe_uP.html      |  14 +++--
 build/ems_ca_me.html         |  10 +++-
 build/ems_ca_me_Ed.html      |  10 +++-
 build/ems_ca_me_Eq.html      |  10 +++-
 build/ems_ca_me_a.html       |  10 +++-
 build/ems_ca_me_h.html       |  18 +++---
 build/ems_ca_me_md.html      |  14 +++--
 build/ems_ca_mi.html         |  10 +++-
 build/ems_ca_mi_fe.html      |  10 +++-
 build/ems_ca_mi_isc.html     |  10 +++-
 build/ems_ca_mi_o.html       |  10 +++-
 build/ems_ca_sv.html         |  10 +++-
 build/ems_ca_sv_car.html     |  14 +++--
 build/ems_ca_sv_cyl.html     |  10 +++-
 build/ems_ca_sv_sph.html     |  18 +++---
 build/ems_es.html            |  18 +++---
 build/ems_es_c.html          |  10 +++-
 build/ems_es_c_cap.html      |  12 ++--
 build/ems_es_c_ic.html       |  12 ++--
 build/ems_es_c_p.html        |  12 ++--
 build/ems_es_c_sc.html       |  10 +++-
 build/ems_es_e.html          |  10 +++-
 build/ems_es_e_c.html        |  10 +++-
 build/ems_es_e_ccd.html      |  14 +++--
 build/ems_es_e_pcd.html      |  10 +++-
 build/ems_es_ec.html         |  10 +++-
 build/ems_es_ec_b.html       |  10 +++-
 build/ems_es_ec_c.html       |  10 +++-
 build/ems_es_ec_q.html       |  10 +++-
 build/ems_es_ec_s.html       |  10 +++-
 build/ems_es_ef.html         |  10 +++-
 build/ems_es_ef_Gl.html      |  32 ++++++-----
 build/ems_es_ef_cE.html      |  22 +++++---
 build/ems_es_ef_ccd.html     |  32 ++++++-----
 build/ems_es_ef_pc.html      |  24 ++++----
 build/ems_es_efo.html        |  10 +++-
 build/ems_es_efo_cl.html     |  20 ++++---
 build/ems_es_efo_e.html      |  22 ++++++--
 build/ems_es_efo_exp.html    |  26 +++++----
 build/ems_es_efo_ps.html     |  12 ++--
 build/ems_es_ep.html         |  10 +++-
 build/ems_es_ep_PL.html      |  14 +++--
 build/ems_es_ep_bc.html      |  10 +++-
 build/ems_es_ep_c.html       |  10 +++-
 build/ems_es_ep_d.html       |  22 +++++---
 build/ems_es_ep_ex.html      |  14 +++--
 build/ems_es_ep_fp.html      |  12 ++--
 build/ems_ms.html            |  18 +++---
 build/ems_ms_BS.html         |  10 +++-
 build/ems_ms_BS_sc.html      |  18 +++---
 build/ems_ms_dcB.html        |  10 +++-
 build/ems_ms_dcB_BS.html     |  24 ++++----
 build/ems_ms_dcB_sc.html     |  12 ++--
 build/ems_ms_lf.html         |  10 +++-
 build/ems_ms_lf_c.html       |  14 +++--
 build/ems_ms_lf_pc.html      |  18 +++---
 build/ems_ms_vp.html         |  24 ++++----
 build/ems_ms_vp_LC.html      |  12 ++--
 build/ems_ms_vp_comp.html    |  10 +++-
 build/ems_ms_vp_mbc.html     |  16 ++++--
 build/ems_ms_vp_me.html      |  18 +++---
 build/emsm.html              |  18 +++---
 build/emsm_esm.html          |  12 ++--
 build/emsm_esm_D.html        |  20 ++++---
 build/emsm_esm_D_bc.html     |  12 ++--
 build/emsm_esm_di.html       |  14 +++--
 build/emsm_esm_di_ld.html    |  36 ++++++------
 build/emsm_esm_fpo.html      |  20 ++++---
 build/emsm_esm_fpo_fid.html  |  12 ++--
 build/emsm_esm_fpo_pibc.html |  10 +++-
 build/emsm_esm_p.html        |  16 ++++--
 build/emsm_esm_s.html        |  10 +++-
 build/emsm_msm.html          |  18 +++---
 build/emsm_msm_H.html        |  10 +++-
 build/emsm_msm_H_A.html      |  18 +++---
 build/emsm_msm_a.html        |  10 +++-
 build/emsm_msm_fmo.html      |  10 +++-
 build/emsm_msm_fmo_bc.html   |  20 ++++---
 build/emsm_msm_fmo_fim.html  |  10 +++-
 build/emsm_msm_fmo_pibc.html |  10 +++-
 build/emsm_msm_lnlm.html     |  10 +++-
 build/emsm_msm_lnlm_fm.html  |  10 +++-
 build/emsm_msm_lnlm_sp.html  |  12 ++--
 build/emsm_msm_m.html        |  10 +++-
 build/emsm_msm_m_dpf.html    |  14 +++--
 build/emsm_msm_m_fdi.html    |  14 +++--
 build/in.html                |  10 +++-
 build/in_p.html              |  33 ++++++++++-
 build/in_t.html              |  13 +++--
 build/in_t_c.html            |  40 +++++++------
 build/index.html             |  13 +++--
 build/qed.html               |  10 +++-
 build/qed_t.html             |  10 +++-
 build/red.html               |  18 +++---
 build/red_rem.html           |  10 +++-
 build/red_rem_Fmunu.html     |  16 ++++--
 build/red_rem_Ltf.html       |  12 ++--
 build/red_rem_Me.html        |  22 +++++---
 build/red_rem_mre.html       |  12 ++--
 build/red_rm.html            |  10 +++-
 build/red_rm_Mf.html         |  16 ++++--
 build/red_rm_pt.html         |  14 +++--
 build/red_rm_rme.html        |  18 +++---
 build/red_sr.html            |  10 +++-
 build/red_sr_4v.html         |  16 ++++--
 build/red_sr_Lt.html         |  12 ++--
 build/red_sr_p.html          |  14 +++--
 207 files changed, 1882 insertions(+), 1097 deletions(-)

diff --git a/build/a.html b/build/a.html
index 386f17d..a1c9672 100644
--- a/build/a.html
+++ b/build/a.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/a_l.html b/build/a_l.html
index ed50e09..46771ad 100644
--- a/build/a_l.html
+++ b/build/a_l.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1712,7 +1716,7 @@ Wiley, 1986 [2nd edition]
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c.html b/build/c.html
index e5f2d8d..3f1a057 100644
--- a/build/c.html
+++ b/build/c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m.html b/build/c_m.html
index 2103581..1e87a4c 100644
--- a/build/c_m.html
+++ b/build/c_m.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1635,7 +1639,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_cs.html b/build/c_m_cs.html
index 0baaa19..c1751dd 100644
--- a/build/c_m_cs.html
+++ b/build/c_m_cs.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_cs_cyl.html b/build/c_m_cs_cyl.html
index dcd94f1..ac082c7 100644
--- a/build/c_m_cs_cyl.html
+++ b/build/c_m_cs_cyl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,47 +1626,39 @@ Table of contents
 \((r, \phi, z)\).  Relation to Cartesian coordinates:
 </p>
 
-<p>
-\[
+\begin{equation}
 x = r \cos \phi, y = r \sin \phi, z = z
 \label{Gr(1.74)}
-\]
-</p>
+\end{equation}
 
 <p>
 The unit vectors are
 </p>
 
-<p>
-\[
+\begin{equation}
 \hat{\bf r} = \cos \phi ~\hat{\bf x} + \sin \phi~\hat{\bf y},
 \hat{\boldsymbol \phi} = -\sin \theta ~\hat{\bf x} + \cos \phi~\hat{\bf y},
 \hat{\bf z} = \hat{\bf z}.
 \label{Gr(1.75)}
-\]
-</p>
+\end{equation}
 
 <p>
 Infinitesimal displacement:
 </p>
 
-<p>
-\[
+\begin{equation}
 d{\bf l} = dr ~\hat{\bf r} + r d\phi~\hat{\boldsymbol \phi} + dz ~\hat{\bf z}.
 \label{Gr(1.77)}
-\]
-</p>
+\end{equation}
 
 <p>
 Volume element:
 </p>
 
-<p>
-\[
+\begin{equation}
 d\tau = r dr d\phi dz
 \label{Gr(1.78)}
-\]
-</p>
+\end{equation}
 
 <p>
 Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in ]-\infty, \infty[\).
@@ -1672,14 +1668,14 @@ Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in
 <div id="outline-container-c_m_cs_cyl_grad" class="outline-6">
 <h6 id="c_m_cs_cyl_grad"><a href="#c_m_cs_cyl_grad">Gradient</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_cyl_grad">
-<div class="eqlabel" id="org1f82008">
+<div class="eqlabel" id="orgc4b6bac">
 <p>
 <a id="cylgrad"></a><a href="./c_m_cs_cyl.html#cylgrad"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org0d07fad">
+<div class="alteqlabels" id="orgdcdbcb4">
 <ul class="org-ul">
 <li>Gr4(1.79)</li>
 </ul>
@@ -1688,32 +1684,26 @@ Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in
 
 </div>
 
-<p>
-\[
-{\boldsymbol ∇} T = \frac{\partial T}{\partial r}~\hat{\bf r}
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r} \frac{\partial T}{\partial \phi}~\hat{\boldsymbol \phi}</li>
-<li>\frac{\partial T}{\partial z} ~\hat{\bf z}</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla} T = \frac{\partial T}{\partial r}~\hat{\bf r}
++ \frac{1}{r} \frac{\partial T}{\partial \phi}~\hat{\boldsymbol \phi}
++ \frac{\partial T}{\partial z} ~\hat{\bf z}
 \tag{cylgrad}\label{cylgrad}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_cyl_div" class="outline-6">
 <h6 id="c_m_cs_cyl_div"><a href="#c_m_cs_cyl_div">Divergence</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_cyl_div">
-<div class="eqlabel" id="org9646f8e">
+<div class="eqlabel" id="orgf9d0262">
 <p>
 <a id="cyl_div"></a><a href="./c_m_cs_cyl.html#cyl_div"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="orgef4d1a0">
+<div class="alteqlabels" id="orgd456be1">
 <ul class="org-ul">
 <li>Gr4(2.21)</li>
 </ul>
@@ -1722,32 +1712,26 @@ Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in
 
 </div>
 
-<p>
-\[
-{\boldsymbol ∇} ⋅ {\bf v} = \frac{1}{r} \frac{\partial}{\partial r} (r v_r)
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r} \frac{∂ v_{φ}}{∂ φ} + \frac{\partial v_z}{\partial z}.</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla} \cdot {\bf v} = \frac{1}{r} \frac{\partial}{\partial r} (r v_r)
++ \frac{1}{r} \frac{\partial v_{\phi}}{\partial \phi} + \frac{\partial v_z}{\partial z}.
 \tag{cyl_div}
 \label{cyl_div}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_cyl_curl" class="outline-6">
 <h6 id="c_m_cs_cyl_curl"><a href="#c_m_cs_cyl_curl">Curl</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_cyl_curl">
-<div class="eqlabel" id="org174b722">
+<div class="eqlabel" id="orgeb922d3">
 <p>
 <a id="cyl_curl"></a><a href="./c_m_cs_cyl.html#cyl_curl"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org9f83d45">
+<div class="alteqlabels" id="org66ae846">
 <ul class="org-ul">
 <li>Gr4(2.21)</li>
 </ul>
@@ -1756,36 +1740,24 @@ Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in
 
 </div>
 
-<p>
-\[
-{\boldsymbol ∇} × {\bf v} = \left( \frac{1}{r} \frac{\partial v_z}{\partial \phi} - \frac{∂ v_{φ}}{∂ z}\right) ~\hat{\bf r}
-</p>
-<ul class="org-ul">
-<li>\left( \frac{\partial v_r}{\partial z} - \frac{\partial v_z}{\partial r} \right) ~\hat{\boldsymbol \phi}</li>
-<li>\frac{1}{r} \left( \frac{\partial}{\partial r} (r v_{φ}) - \frac{\partial v_r}{\partial \phi} \right) ~\hat{\bf z}</li>
-</ul>
-<p>
+\begin{align}
+{\boldsymbol \nabla} \times {\bf v} = \left( \frac{1}{r} \frac{\partial v_z}{\partial \phi} - \frac{\partial v_{\phi}}{\partial z}\right) ~\hat{\bf r}
++ \left( \frac{\partial v_r}{\partial z} - \frac{\partial v_z}{\partial r} \right) ~\hat{\boldsymbol \phi} \nonumber \\
++ \frac{1}{r} \left( \frac{\partial}{\partial r} (r v_{\phi}) - \frac{\partial v_r}{\partial \phi} \right) ~\hat{\bf z}
 \tag{cyl_curl}
 \label{cyl_curl}
-\]
-</p>
+\end{align}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_cyl_lap" class="outline-6">
 <h6 id="c_m_cs_cyl_lap"><a href="#c_m_cs_cyl_lap">Laplacian</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_cyl_lap">
-<p>
-\[
-{\boldsymbol ∇}^2 T = \frac{1}{r} \frac{\partial}{\partial r} \left( r \frac{\partial T}{\partial r} \right)
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r^2} \frac{\partial^2 T}{\partial \phi^2} + \frac{\partial^2 T}{\partial z^2}</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla}^2 T = \frac{1}{r} \frac{\partial}{\partial r} \left( r \frac{\partial T}{\partial r} \right)
++ \frac{1}{r^2} \frac{\partial^2 T}{\partial \phi^2} + \frac{\partial^2 T}{\partial z^2}
 \label{Gr(1.82)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 </div>
@@ -1795,7 +1767,7 @@ Range of parameters:  \(r \in [0, \infty[\), \(\phi \in [0, 2\pi[\) and \(z \in
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_cs_hyp.html b/build/c_m_cs_hyp.html
index 6342d80..f36ae93 100644
--- a/build/c_m_cs_hyp.html
+++ b/build/c_m_cs_hyp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,7 +1628,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_cs_sph.html b/build/c_m_cs_sph.html
index c46a505..c854513 100644
--- a/build/c_m_cs_sph.html
+++ b/build/c_m_cs_sph.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1688,70 +1692,46 @@ Infinitesimal surface element:  depends on situation.
 <div id="outline-container-c_m_cs_sph_grad" class="outline-6">
 <h6 id="c_m_cs_sph_grad"><a href="#c_m_cs_sph_grad">Gradient</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_sph_grad">
-<p>
-\[
-{\boldsymbol ∇} T = \frac{\partial T}{\partial r} \hat{\boldsymbol r} + \frac{1}{r} \frac{\partial T}{\partial \theta} \hat{\boldsymbol \theta}
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r\sin \theta} \frac{\partial T}{\partial \phi} \hat{\boldsymbol \phi}.</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla} T = \frac{\partial T}{\partial r} \hat{\boldsymbol r} + \frac{1}{r} \frac{\partial T}{\partial \theta} \hat{\boldsymbol \theta}
++ \frac{1}{r\sin \theta} \frac{\partial T}{\partial \phi} \hat{\boldsymbol \phi}.
 \label{Gr(1.70)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_sph_div" class="outline-6">
 <h6 id="c_m_cs_sph_div"><a href="#c_m_cs_sph_div">Divergence</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_sph_div">
-<p>
-\[
-{\boldsymbol ∇} ⋅ {\bf v} = \frac{1}{r^2} \frac{\partial}{\partial r} (r^2 v_r) + \frac{1}{r\sin \theta} \frac{\partial}{\partial \theta} (sinθ v_{θ})
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r \sin \theta} \frac{∂ v_{φ}}{∂ φ}</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla} \cdot {\bf v} = \frac{1}{r^2} \frac{\partial}{\partial r} (r^2 v_r) + \frac{1}{r\sin \theta} \frac{\partial}{\partial \theta} (\sin\theta v_{\theta})
++ \frac{1}{r \sin \theta} \frac{\partial v_{\phi}}{\partial \phi}
 \label{Gr(1.71)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_sph_curl" class="outline-6">
 <h6 id="c_m_cs_sph_curl"><a href="#c_m_cs_sph_curl">Curl</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_sph_curl">
-<p>
-\[
-{\boldsymbol ∇} × {\bf v} = \frac{1}{r\sin \theta} \left[ \frac{\partial}{\partial \theta} (sin θ v_{φ}) - \frac{∂ v_{θ}}{∂ φ} \right] \hat{\bf r}
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r} \left[ \frac{1}{\sin \theta} \frac{\partial v_r}{\partial \phi} - \frac{\partial}{\partial r} (r v_{φ}) \right] \hat{\boldsymbol \theta}</li>
-<li>\frac{1}{r} \left[ \frac{\partial}{\partial r} (r v_{θ}) - \frac{\partial v_r}{\partial \theta} \right] \hat{\boldsymbol \phi}</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla} \times {\bf v} = \frac{1}{r\sin \theta} \left[ \frac{\partial}{\partial \theta} (\sin \theta v_{\phi}) - \frac{\partial v_{\theta}}{\partial \phi} \right] \hat{\bf r}
++ \frac{1}{r} \left[ \frac{1}{\sin \theta} \frac{\partial v_r}{\partial \phi} - \frac{\partial}{\partial r} (r v_{\phi}) \right] \hat{\boldsymbol \theta}
++ \frac{1}{r} \left[ \frac{\partial}{\partial r} (r v_{\theta}) - \frac{\partial v_r}{\partial \theta} \right] \hat{\boldsymbol \phi}
 \label{Gr(1.72)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 <div id="outline-container-c_m_cs_sph_lap" class="outline-6">
 <h6 id="c_m_cs_sph_lap"><a href="#c_m_cs_sph_lap">Laplacian</a></h6>
 <div class="outline-text-6" id="text-c_m_cs_sph_lap">
-<p>
-\[
-{\boldsymbol ∇}^2 T = \frac{1}{r^2} \frac{\partial}{\partial r} \left(r^2 \frac{\partial T}{\partial r}\right)
-</p>
-<ul class="org-ul">
-<li>\frac{1}{r^2 \sin \theta} \frac{\partial}{\partial \theta} \left( sin θ \frac{\partial T}{\partial \theta}\right)</li>
-<li>\frac{1}{r^2 \sin^2 \theta} \frac{\partial^2 T}{\partial \phi^2}</li>
-</ul>
-<p>
+\begin{equation}
+{\boldsymbol \nabla}^2 T = \frac{1}{r^2} \frac{\partial}{\partial r} \left(r^2 \frac{\partial T}{\partial r}\right)
++ \frac{1}{r^2 \sin \theta} \frac{\partial}{\partial \theta} \left( \sin \theta \frac{\partial T}{\partial \theta}\right)
++ \frac{1}{r^2 \sin^2 \theta} \frac{\partial^2 T}{\partial \phi^2}
 \label{Gr(1.73)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 </div>
@@ -1761,7 +1741,7 @@ Infinitesimal surface element:  depends on situation.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc.html b/build/c_m_dc.html
index 7672054..29d8848 100644
--- a/build/c_m_dc.html
+++ b/build/c_m_dc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1634,7 +1638,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_curl.html b/build/c_m_dc_curl.html
index 55e5cdf..fb804be 100644
--- a/build/c_m_dc_curl.html
+++ b/build/c_m_dc_curl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1636,7 +1640,7 @@ v_x &amp; v_y &amp; v_z \end{array} \right| \nonumber \\
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_d2.html b/build/c_m_dc_d2.html
index cf3310e..f286af4 100644
--- a/build/c_m_dc_d2.html
+++ b/build/c_m_dc_d2.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1620,9 +1624,9 @@ Table of contents
 <div class="outline-text-5" id="text-c_m_dc_d2">
 </div>
 
-<div id="outline-container-orgc3b89bb" class="outline-6">
-<h6 id="orgc3b89bb"><a href="#orgc3b89bb">Divergence of gradient</a></h6>
-<div class="outline-text-6" id="text-orgc3b89bb">
+<div id="outline-container-org5fd48d1" class="outline-6">
+<h6 id="org5fd48d1"><a href="#org5fd48d1">Divergence of gradient</a></h6>
+<div class="outline-text-6" id="text-org5fd48d1">
 <p>
 \({\boldsymbol \nabla} \cdot ({\boldsymbol \nabla} T) \equiv {\boldsymbol \nabla}^2 T\) is called the <b>Laplacian</b> of the scalar field \(T\).
 The Laplacian of a vector field \({\boldsymbol \nabla}^2 {\bf v}\) is also defined as the vector with components
@@ -1631,36 +1635,36 @@ given by the Laplacian of the corresponding vector elements.
 </div>
 </div>
 
-<div id="outline-container-org5caf3f5" class="outline-6">
-<h6 id="org5caf3f5"><a href="#org5caf3f5">Curl of a gradient</a></h6>
-<div class="outline-text-6" id="text-org5caf3f5">
+<div id="outline-container-org41a3448" class="outline-6">
+<h6 id="org41a3448"><a href="#org41a3448">Curl of a gradient</a></h6>
+<div class="outline-text-6" id="text-org41a3448">
 <p>
 This always vanishes.
 </p>
 </div>
 </div>
 
-<div id="outline-container-org4f9116a" class="outline-6">
-<h6 id="org4f9116a"><a href="#org4f9116a">Gradient of the divergence</a></h6>
-<div class="outline-text-6" id="text-org4f9116a">
+<div id="outline-container-org6c4b5a7" class="outline-6">
+<h6 id="org6c4b5a7"><a href="#org6c4b5a7">Gradient of the divergence</a></h6>
+<div class="outline-text-6" id="text-org6c4b5a7">
 <p>
 \({\boldsymbol \nabla} ({\boldsymbol \nabla} \cdot {\bf v})\) does not appear often in physics.  No special name.
 </p>
 </div>
 </div>
 
-<div id="outline-container-org2c1c081" class="outline-6">
-<h6 id="org2c1c081"><a href="#org2c1c081">Divergence of a curl</a></h6>
-<div class="outline-text-6" id="text-org2c1c081">
+<div id="outline-container-org68b62ab" class="outline-6">
+<h6 id="org68b62ab"><a href="#org68b62ab">Divergence of a curl</a></h6>
+<div class="outline-text-6" id="text-org68b62ab">
 <p>
 This always vanishes.
 </p>
 </div>
 </div>
 
-<div id="outline-container-orgc977e97" class="outline-6">
-<h6 id="orgc977e97"><a href="#orgc977e97">Curl of curl</a></h6>
-<div class="outline-text-6" id="text-orgc977e97">
+<div id="outline-container-org62690be" class="outline-6">
+<h6 id="org62690be"><a href="#org62690be">Curl of curl</a></h6>
+<div class="outline-text-6" id="text-org62690be">
 <p>
 \[
 {\boldsymbol \nabla} \times ({\boldsymbol \nabla} \times {\bf v}) = {\boldsymbol \nabla} ({\boldsymbol \nabla} \cdot {\bf v}) - {\boldsymbol \nabla}^2 {\bf v}
@@ -1674,7 +1678,7 @@ This always vanishes.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_del.html b/build/c_m_dc_del.html
index 646c045..38c6237 100644
--- a/build/c_m_dc_del.html
+++ b/build/c_m_dc_del.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1635,7 +1639,7 @@ The <b>del/grad/nabla operator</b> is defined as
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_div.html b/build/c_m_dc_div.html
index 4609351..baad0fe 100644
--- a/build/c_m_dc_div.html
+++ b/build/c_m_dc_div.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_g.html b/build/c_m_dc_g.html
index 30a343d..32a09f6 100644
--- a/build/c_m_dc_g.html
+++ b/build/c_m_dc_g.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1656,7 +1660,7 @@ is a vector called the <b>gradient</b> of \(T\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dc_pr.html b/build/c_m_dc_pr.html
index e4b8301..4f01eb3 100644
--- a/build/c_m_dc_pr.html
+++ b/build/c_m_dc_pr.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Six product rules (on inside front cover of Gr).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dd.html b/build/c_m_dd.html
index 8c833ed..b47001d 100644
--- a/build/c_m_dd.html
+++ b/build/c_m_dd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dd_1d.html b/build/c_m_dd_1d.html
index e7d8a81..ea993df 100644
--- a/build/c_m_dd_1d.html
+++ b/build/c_m_dd_1d.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1643,7 +1647,7 @@ Consequences:  for any smooth differentiable function \(f(x)\),
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dd_3d.html b/build/c_m_dd_3d.html
index 5915f4f..ea8ad45 100644
--- a/build/c_m_dd_3d.html
+++ b/build/c_m_dd_3d.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,43 +1622,37 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">c.m.dd.3d</span></h5>
 <div class="outline-text-5" id="text-c_m_dd_3d">
-<p>
-\[
+\begin{equation}
 \delta^{(3)} ({\bf r} - {\bf r}') = \delta (x - x') \delta (y - y') \delta (z - z')
 \label{Gr(1.96)}
-\]
-</p>
+\end{equation}
 
-<p>
-\[
+\begin{equation}
 \int d\tau f({\bf r}) \delta^{(3)} ({\bf r} - {\bf a}) = f({\bf a})
 \label{Gr(1.97)}
-\]
-</p>
+\end{equation}
 
 <p>
 Resolution of divergence of \(\hat{\bf r}/r^2\) paradox:
 </p>
 
-<p>
-\[
+\begin{equation}
 {\boldsymbol \nabla} \cdot \left(\frac{\hat{\bf r}}{r^2} \right)= 4\pi \delta^{(3)} ({\bf r}).
 \label{Gr(1.99)}
-\]
-</p>
+\end{equation}
 
 <p>
 More generally,
 </p>
 
-<div class="eqlabel" id="org99c1900">
+<div class="eqlabel" id="org276d185">
 <p>
 <a id="divdel"></a><a href="./c_m_dd_3d.html#divdel"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="orge7a14d6">
+<div class="alteqlabels" id="org676b181">
 <ul class="org-ul">
 <li>Gr (1.100)</li>
 </ul>
@@ -1662,43 +1660,37 @@ More generally,
 </div>
 
 </div>
-<p>
-\[
+\begin{equation}
 \boxed{
 {\boldsymbol \nabla} \cdot \left(\frac{{\bf r} - {\bf r}'}{|{\bf r} - {\bf r}'|^3} \right)= 4\pi \delta^{(3)} ({\bf r}).
 }
 \tag{divdel}\label{divdel}
-\]
-</p>
+\end{equation}
 
 <p>
 Since
 </p>
 
-<p>
-\[
+\begin{equation}
 {\boldsymbol \nabla}_1 \left(\frac{1}{r_{12}}\right) = -\frac{\hat{\bf r}_{12}}{r_{12}^2}
 \label{Gr(1.101)}
-\]
-</p>
+\end{equation}
 
 <p>
 we have that
 </p>
 
-<p>
-\[
+\begin{equation}
 {\boldsymbol \nabla}^2 \left( \frac{1}{|{\bf r} - {\bf r}'|} \right) = -4\pi \delta^{(3)} ({\bf r} - {\bf r}')
 \label{Gr(1.102)}
-\]
-</p>
+\end{equation}
 </div>
 </div>
 
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_dd_div.html b/build/c_m_dd_div.html
index 8e8c87f..89ff57d 100644
--- a/build/c_m_dd_div.html
+++ b/build/c_m_dd_div.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,12 +1626,10 @@ Table of contents
 Try to calculate this directly:
 </p>
 
-<p>
-\[
+\begin{equation}
 {\boldsymbol \nabla} \cdot \frac{\hat{\bf r}}{r^2} = \frac{1}{r^2} \frac{\partial}{\partial r} \left( r^2 \frac{1}{r^2}\right) =^{?} 0
 \label{Gr(1.84)}
-\]
-</p>
+\end{equation}
 
 <p>
 Now apply the divergence theorem.
@@ -1635,16 +1637,14 @@ Integrate over a sphere of radius \(R\) centered at the origin (Prob.  1.38b):
 </p>
 
 
-<p>
-\[
+\begin{equation}
 \oint \frac{\hat{\bf r}}{r^2} \cdot d{\bf a} = \int \left(\frac{1}{R^2} \hat{\bf r} \right) \cdot \left( R^2 \sin \theta d\theta d\phi ~\hat{\bf r} \right)
 = \int_0^{\pi} d\theta \sin \theta \int_0^{2\pi} d\phi = 4\pi
 \label{Gr(1.85)}
-\]
-</p>
+\end{equation}
 
 <p>
-Problem:  in (1.84), we've divided by zero when \(r = 0\).
+Problem:  in Gr(1.84), we've divided by zero when \(r = 0\).
 </p>
 </div>
 </div>
@@ -1653,7 +1653,7 @@ Problem:  in (1.84), we've divided by zero when \(r = 0\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic.html b/build/c_m_ic.html
index 75eb64e..51a6fa2 100644
--- a/build/c_m_ic.html
+++ b/build/c_m_ic.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1634,7 +1638,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_ftc.html b/build/c_m_ic_ftc.html
index 6fe777d..79f9b98 100644
--- a/build/c_m_ic_ftc.html
+++ b/build/c_m_ic_ftc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_ftg.html b/build/c_m_ic_ftg.html
index 3a0456a..cd89d0d 100644
--- a/build/c_m_ic_ftg.html
+++ b/build/c_m_ic_ftg.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1641,7 +1645,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_gauss.html b/build/c_m_ic_gauss.html
index e9464e8..8d6179c 100644
--- a/build/c_m_ic_gauss.html
+++ b/build/c_m_ic_gauss.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1635,7 +1639,7 @@ This is know either as <b>Gauss' theorem</b>, <b>Green's theorem</b> or the <b>d
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_ip.html b/build/c_m_ic_ip.html
index 9a18cf9..a23eb7c 100644
--- a/build/c_m_ic_ip.html
+++ b/build/c_m_ic_ip.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1642,7 +1646,7 @@ or in other words
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_lsv.html b/build/c_m_ic_lsv.html
index fde2ff3..9b89b48 100644
--- a/build/c_m_ic_lsv.html
+++ b/build/c_m_ic_lsv.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
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@@ -736,7 +740,7 @@ Table of contents
 
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-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
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 <div class="outline-text-5" id="text-c_m_ic_lsv">
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-<div id="outline-container-org860e5de" class="outline-6">
-<h6 id="org860e5de"><a href="#org860e5de">Line Integrals</a></h6>
-<div class="outline-text-6" id="text-org860e5de">
+<div id="outline-container-org609a3df" class="outline-6">
+<h6 id="org609a3df"><a href="#org609a3df">Line Integrals</a></h6>
+<div class="outline-text-6" id="text-org609a3df">
 <p>
 \[
 {\int_{\bf a}^{\bf b}}_{\cal P} {\bf v} \cdot d{\bf l}
@@ -1651,9 +1655,9 @@ Integral over a closed loop:
 </div>
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-<div id="outline-container-orged48130" class="outline-6">
-<h6 id="orged48130"><a href="#orged48130">Surface Integrals</a></h6>
-<div class="outline-text-6" id="text-orged48130">
+<div id="outline-container-org8f657b7" class="outline-6">
+<h6 id="org8f657b7"><a href="#org8f657b7">Surface Integrals</a></h6>
+<div class="outline-text-6" id="text-org8f657b7">
 <p>
 \[
 \int_{\cal S} {\bf v} \cdot d{\bf a}
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-<div id="outline-container-org4728536" class="outline-6">
-<h6 id="org4728536"><a href="#org4728536">Volume Integrals</a></h6>
-<div class="outline-text-6" id="text-org4728536">
+<div id="outline-container-org2ec267e" class="outline-6">
+<h6 id="org2ec267e"><a href="#org2ec267e">Volume Integrals</a></h6>
+<div class="outline-text-6" id="text-org2ec267e">
 <p>
 \[
 \int_{\cal V} T d\tau
@@ -1703,7 +1707,7 @@ d\tau = dx dy dz
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_ic_stokes.html b/build/c_m_ic_stokes.html
index be76a7a..5507208 100644
--- a/build/c_m_ic_stokes.html
+++ b/build/c_m_ic_stokes.html
@@ -1,7 +1,7 @@
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 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
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 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
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+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
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@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
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@@ -1657,7 +1661,7 @@ the boundary shrinks to a point.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_uf.html b/build/c_m_uf.html
index 879c3a6..183c63e 100644
--- a/build/c_m_uf.html
+++ b/build/c_m_uf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
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@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
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@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_uf_cyl.html b/build/c_m_uf_cyl.html
index 6626a83..1d64223 100644
--- a/build/c_m_uf_cyl.html
+++ b/build/c_m_uf_cyl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
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-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1644,7 +1648,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_uf_sph.html b/build/c_m_uf_sph.html
index a7037af..eb7ff66 100644
--- a/build/c_m_uf_sph.html
+++ b/build/c_m_uf_sph.html
@@ -1,7 +1,7 @@
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 <html lang="en">
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-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1644,7 +1648,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_uf_vi.html b/build/c_m_uf_vi.html
index edda436..92b456c 100644
--- a/build/c_m_uf_vi.html
+++ b/build/c_m_uf_vi.html
@@ -1,7 +1,7 @@
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 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1647,7 +1651,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va.html b/build/c_m_va.html
index 7cfec77..137bcbc 100644
--- a/build/c_m_va.html
+++ b/build/c_m_va.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1633,7 +1637,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va_cp.html b/build/c_m_va_cp.html
index fb6f855..2bb79dd 100644
--- a/build/c_m_va_cp.html
+++ b/build/c_m_va_cp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1662,7 +1666,7 @@ this relation making plain that
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va_n.html b/build/c_m_va_n.html
index b7121f6..5550c69 100644
--- a/build/c_m_va_n.html
+++ b/build/c_m_va_n.html
@@ -1,7 +1,7 @@
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 <html lang="en">
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-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1657,7 +1661,7 @@ Component notation (in \({\mathbb R}^3\) with cartesian coordinates):
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va_pds.html b/build/c_m_va_pds.html
index 7e2e3d1..2fd38b7 100644
--- a/build/c_m_va_pds.html
+++ b/build/c_m_va_pds.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1691,7 +1695,7 @@ Separation vector:  for two position vectors \({\bf r}_a, {\bf r}_b\),
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va_sp.html b/build/c_m_va_sp.html
index ab06601..bb4a4a1 100644
--- a/build/c_m_va_sp.html
+++ b/build/c_m_va_sp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1657,7 +1661,7 @@ In a general coordinate system with metric \(g\),
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_va_tp.html b/build/c_m_va_tp.html
index 7d20350..e337799 100644
--- a/build/c_m_va_tp.html
+++ b/build/c_m_va_tp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1704,7 +1708,7 @@ All higher vector products can be reduced to combinations of single vector produ
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_vf.html b/build/c_m_vf.html
index 40bf079..94c835e 100644
--- a/build/c_m_vf.html
+++ b/build/c_m_vf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_vf_helm.html b/build/c_m_vf_helm.html
index 7668a92..9fd0c6d 100644
--- a/build/c_m_vf_helm.html
+++ b/build/c_m_vf_helm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1649,7 +1653,7 @@ where
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/c_m_vf_pot.html b/build/c_m_vf_pot.html
index 2d3c351..74eb6bc 100644
--- a/build/c_m_vf_pot.html
+++ b/build/c_m_vf_pot.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1623,12 +1627,10 @@ If the curl of a vector field \({\bf F}\) vanishes, then \({\bf F}\) can be writ
 <b>scalar potential</b> \(V\):
 </p>
 
-<p>
-\[
+\begin{equation}
 {\boldsymbol \nabla} \times {\bf F} = 0 \Longleftrightarrow {\bf F} = -{\boldsymbol \nabla} V
 \label{Gr(1.103)}
-\]
-</p>
+\end{equation}
 </div>
 
 <div id="outline-container-c_m_vf_pot_irrot" class="outline-6">
@@ -1678,7 +1680,7 @@ The following conditions are equivalent:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d.html b/build/d.html
index 05262db..2d2f82a 100644
--- a/build/d.html
+++ b/build/d.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">d</span></h2>
 
 <div class="outline-text-2" id="text-d">
-<details class="objectives" id="org8e87179">
-<summary id="org5aefd0c">
+<details class="objectives" id="orgdc678ad">
+<summary id="org6e8a387">
 Objectives
 </summary>
 
@@ -1671,7 +1675,7 @@ I have little doubt you'll pass the course.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emd.html b/build/d_emd.html
index 1b899c8..fbbcec6 100644
--- a/build/d_emd.html
+++ b/build/d_emd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1651,7 +1655,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emd_ce.html b/build/d_emd_ce.html
index 6c6bb5e..53435fc 100644
--- a/build/d_emd_ce.html
+++ b/build/d_emd_ce.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1646,7 +1650,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emd_emw.html b/build/d_emd_emw.html
index bec85f1..ff868bc 100644
--- a/build/d_emd_emw.html
+++ b/build/d_emd_emw.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1649,7 +1653,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emf.html b/build/d_emf.html
index 9bba6fa..7fc5719 100644
--- a/build/d_emf.html
+++ b/build/d_emf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1646,7 +1650,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_ems.html b/build/d_ems.html
index cb083bb..31de60e 100644
--- a/build/d_ems.html
+++ b/build/d_ems.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1668,7 +1672,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_ems_ca.html b/build/d_ems_ca.html
index 937ed32..d775891 100644
--- a/build/d_ems_ca.html
+++ b/build/d_ems_ca.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1651,7 +1655,7 @@ a point source charge \(q\) at \({\bf r}_s\) with an infinite grounded conductin
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_ems_ms.html b/build/d_ems_ms.html
index 957080c..ba8a9f6 100644
--- a/build/d_ems_ms.html
+++ b/build/d_ems_ms.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1648,7 +1652,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emsm.html b/build/d_emsm.html
index 9603293..ecdd13e 100644
--- a/build/d_emsm.html
+++ b/build/d_emsm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1651,7 +1655,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_emsm_msm.html b/build/d_emsm_msm.html
index 7430bf3..2221e8e 100644
--- a/build/d_emsm_msm.html
+++ b/build/d_emsm_msm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1649,7 +1653,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_m.html b/build/d_m.html
index e439a56..0b48535 100644
--- a/build/d_m.html
+++ b/build/d_m.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1659,7 +1663,7 @@ Things you should be able to do (ideally: from scratch, on a blank sheet of pape
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/d_red.html b/build/d_red.html
index 6455be5..5ce716c 100644
--- a/build/d_red.html
+++ b/build/d_red.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1653,7 +1657,7 @@ As a strict minimum, you should be able to:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd.html b/build/emd.html
index cccc3f1..e88ec90 100644
--- a/build/emd.html
+++ b/build/emd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emd</span></h2>
 
 <div class="outline-text-2" id="text-emd">
-<details class="prereq" id="orgfca423d">
-<summary id="org226d692">
+<details class="prereq" id="org91070ea">
+<summary id="orgec443fc">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1629,8 +1633,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org9195c9d">
-<summary id="org58d183b">
+<details class="objectives" id="org7a852ae">
+<summary id="org301eba1">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1658,7 +1662,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Fl.html b/build/emd_Fl.html
index 715cce4..697b018 100644
--- a/build/emd_Fl.html
+++ b/build/emd_Fl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Fl_Fl.html b/build/emd_Fl_Fl.html
index f9da649..eea9f62 100644
--- a/build/emd_Fl_Fl.html
+++ b/build/emd_Fl_Fl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1659,7 +1663,7 @@ Empirically:  the changing magnetic field induces an electric current around
 the circuit. This current is really driven by an electric field having a component
 along the wire.  The line integral of this field is called the
 </p>
-<div class="core div" id="org9907fe5">
+<div class="core div" id="orgcb2b8bd">
 <p>
 <b>Electromotive force (or electromotance)</b>,
   \[
@@ -1681,7 +1685,7 @@ to the rate of change of the magnetic flux,
 \]
 so we obtain
 </p>
-<div class="core div" id="org511a243">
+<div class="core div" id="org826bbb5">
 <p>
 <b>Faraday's law</b> (integral form <i>N.B.: for a stationary loop</i>)
   \[
@@ -1699,7 +1703,7 @@ for any loop (on a wire or not). Using Stokes' theorem,
 \]
 we obtain
 </p>
-<div class="core div" id="orgb9e0e05">
+<div class="core div" id="org4f576bd">
 <p>
 <b>Faraday's law</b> (differential form)
   \[
@@ -1723,7 +1727,7 @@ to an opposing counter-reaction.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Fl_e.html b/build/emd_Fl_e.html
index bd0874e..f4da0de 100644
--- a/build/emd_Fl_e.html
+++ b/build/emd_Fl_e.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1678,7 +1682,7 @@ W = \frac{1}{2\mu_0} \left[ \int_{\cal V} d\tau B^2 - \int_{\cal V} d\tau {\bold
 \]
 We can integrate over all space:  after neglecting boundary terms (assuming fields fall to zero at infinity), we are left with
 </p>
-<div class="core div" id="org0a53c4e">
+<div class="core div" id="org612a7d5">
 <p>
 \[
     W_{mag} = \frac{1}{2\mu_0} \int d\tau B^2
@@ -1699,7 +1703,7 @@ W_{mag} = \frac{1}{2} \int d\tau ({\bf A} \cdot {\bf J}) = \frac{1}{2\mu_0} \int
 \hspace{2cm} \mbox{(7.31 and 7.34)}
 \end{align}
 
-<div class="example div" id="orge7b1ecf">
+<div class="example div" id="org8806452">
 <p>
 \paragraph{Example 7.13:}  coaxial cable (inner cylinder radius \(a\), outer \(b\)) carries current \(I\).
 Find energy stored in section of length \(l\).
@@ -1725,7 +1729,7 @@ Note:  gives easy way to find inductance, since \(W = \frac{1}{2} L I^2\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Fl_i.html b/build/emd_Fl_i.html
index eda2671..7150747 100644
--- a/build/emd_Fl_i.html
+++ b/build/emd_Fl_i.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1658,7 +1662,7 @@ M_{12} = M_{21}
 \]
 </p>
 
-<div class="example div" id="orgc2d0a32">
+<div class="example div" id="org105c83a">
 <p>
 \paragraph{Example 7.10:}
 short solenoid (length \(l\), radius \(a\), \(n_1\) turns per unit length) lies concentrically inside
@@ -1708,7 +1712,7 @@ Inductance:  measured in {\bf henries} (\(H\)).  \(H = V s/A\).
 </p>
 
 
-<div class="example div" id="org7f4b3fa">
+<div class="example div" id="orgfde0fbc">
 <p>
 \paragraph{Example 7.11:}  find self-inductance of toroidal coil with
 rectangular cross-section (inner radius \(a\), outer radius \(b\), height \(h\))
@@ -1735,7 +1739,7 @@ Total flux:  \(N\) times this, so self-inductance is
 Inductance (like capacitance) is intrinsically positive.  Use Lenz law.  Think of {\bf back EMF}.
 </p>
 
-<div class="example div" id="org37841ae">
+<div class="example div" id="org88909b4">
 <p>
 \paragraph{Example 7.12:}  circuit with inductance \(L\), resistor \(R\) and battery \({\cal E}_0\).
 What is the current ?
@@ -1761,7 +1765,7 @@ where \(\tau \equiv L/R\) is the {\bf time constant} of the circuit.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Fl_ief.html b/build/emd_Fl_ief.html
index 9246b27..b54f403 100644
--- a/build/emd_Fl_ief.html
+++ b/build/emd_Fl_ief.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1642,7 +1646,7 @@ law in integral form:
 
 
 
-<div class="example div" id="orgfe52c32">
+<div class="example div" id="org6f81c6a">
 <p>
 {\bf Example 7.7:}
 \({\bf B}(t)\) points up in circular region of radius \(R\).  What is the induced \({\bf E}(t)\) ?
@@ -1658,7 +1662,7 @@ Increasing \({\bf B}\):  clockwise (viewed from above) \({\bf E}\) from Lenz.
 </div>
 
 
-<div class="example div" id="orgb289794">
+<div class="example div" id="org5fbf230">
 <p>
 {\bf Example 7.8:} wheel or radius \(b\) with line charge \(\lambda\) on the rim.
 Uniform magnetic field \({\bf B}_0\) in central region up to \(a &lt; b\),
@@ -1692,7 +1696,7 @@ called the {\bf quasistatic} approximation, and works provided we deal with
 'slow enough' phenomena.
 </p>
 
-<div class="example div" id="orgd4a9b9d">
+<div class="example div" id="org4c83960">
 <p>
 {\bf Example 7.9:}  infinitely long straight wire carries \(I(t)\).  Find
 induced \({\bf E}\) field as a function of distance \(s\) from wire.
@@ -1727,7 +1731,7 @@ Reason:  in this case, we've overstepped the quasistatic limit.  We need
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Me.html b/build/emd_Me.html
index 849eb15..2d9750c 100644
--- a/build/emd_Me.html
+++ b/build/emd_Me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Me_Me.html b/build/emd_Me_Me.html
index bc5397e..3b01f84 100644
--- a/build/emd_Me_Me.html
+++ b/build/emd_Me_Me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 Full set of equations for the electromagnetic field:
 </p>
-<div class="core div" id="org152d250">
+<div class="core div" id="org61cd67c">
 <p>
 {\bf Maxwell's equations} {\it (in vacuum)}
 </p>
@@ -1637,7 +1641,7 @@ Full set of equations for the electromagnetic field:
 <p>
 Complement:
 </p>
-<div class="core div" id="org1c66368">
+<div class="core div" id="org2b8e704">
 <p>
 {\bf Force law}
 \[
@@ -1661,7 +1665,7 @@ take divergence of \((iv)\).
 <p>
 Better way of writing:  all fields on left, all sources on right,
 </p>
-<div class="core div" id="org1958d41">
+<div class="core div" id="orgac16379">
 \begin{align}
   (i) &amp;{\boldsymbol \nabla} \cdot {\bf E} = \frac{\rho}{\varepsilon_0},
   &amp;(iii) {\boldsymbol \nabla} \times {\bf E} + \frac{\partial {\bf B}}{\partial t} = 0, \\
@@ -1678,7 +1682,7 @@ Better way of writing:  all fields on left, all sources on right,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Me_dc.html b/build/emd_Me_dc.html
index 56c79b3..9b723f4 100644
--- a/build/emd_Me_dc.html
+++ b/build/emd_Me_dc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,7 +1632,7 @@ the continuity equation as
 \]
 The extra term would thus be eliminated if we were to put
 </p>
-<div class="core div" id="orgff64dd3">
+<div class="core div" id="orgc09ac90">
 <p>
 \[
     {\boldsymbol \nabla} \times {\bf B} = \mu_0 {\bf J} + \mu_0 \varepsilon_0 \frac{\partial {\bf E}}{\partial t}
@@ -1652,7 +1656,7 @@ Real confirmation of Maxwell's theory:  1888, Hertz's experiments on propagation
 <p>
 Maxwell baptized this term the
 </p>
-<div class="core div" id="org4206404">
+<div class="core div" id="orgd2c9b8e">
 <p>
 {\bf Displacement current}
 \[
@@ -1687,7 +1691,7 @@ Flat surface:  OK, \(E = 0\) and \(I_{\mbox{enc}} = I\).  Balloon surface:  \(I
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Me_ebM.html b/build/emd_Me_ebM.html
index a7fb7a3..bb5dcb2 100644
--- a/build/emd_Me_ebM.html
+++ b/build/emd_Me_ebM.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1657,7 +1661,7 @@ So for non-steady currents, the 'current enclosed by a loop' is ill-defined.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_Me_mc.html b/build/emd_Me_mc.html
index d9fd932..8bef4fa 100644
--- a/build/emd_Me_mc.html
+++ b/build/emd_Me_mc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1655,7 +1659,7 @@ Maxwell's equations {\bf beg} for magnetic charges.  But we've never found any!
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce.html b/build/emd_ce.html
index 809bf09..b51fbbd 100644
--- a/build/emd_ce.html
+++ b/build/emd_ce.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emd.ce</span></h3>
 
 <div class="outline-text-3" id="text-emd_ce">
-<details class="prereq" id="orge209dc2">
-<summary id="org650a07d">
+<details class="prereq" id="orgcfe0487">
+<summary id="orge8a2c1d">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1628,8 +1632,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org4962fbd">
-<summary id="org509fe5e">
+<details class="objectives" id="org87970ae">
+<summary id="org29e69c3">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1654,7 +1658,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce_amom.html b/build/emd_ce_amom.html
index 53ea4f9..d68357a 100644
--- a/build/emd_ce_amom.html
+++ b/build/emd_ce_amom.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 The angular momentum of EM fields is directly given by
 </p>
-<div class="main div" id="org3de73d0">
+<div class="main div" id="org15be82e">
 <p>
 {\bf Angular momentum of EM fields}
 \[
@@ -1638,7 +1642,7 @@ The angular momentum of EM fields is directly given by
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce_ce.html b/build/emd_ce_ce.html
index 1a46624..7079275 100644
--- a/build/emd_ce_ce.html
+++ b/build/emd_ce_ce.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1640,7 +1644,7 @@ This means that
 \]
 Since this is true for any volume, we have (re)derived the
 </p>
-<div class="core div" id="org20202cd">
+<div class="core div" id="orgf7fdcf4">
 <p>
 {\bf Continuity equation}
 \[
@@ -1668,7 +1672,7 @@ imposes a functional constraint on these sources: not {\it any} \(\rho\) and
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce_mom.html b/build/emd_ce_mom.html
index 4738e76..8882f02 100644
--- a/build/emd_ce_mom.html
+++ b/build/emd_ce_mom.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1633,7 +1637,7 @@ in which the first integral can be interpreted as the momentum stored in the EM
 <p>
 This is thus simply a conservation law for momentum, with
 </p>
-<div class="main div" id="org2bb42ec">
+<div class="main div" id="orgeb408ef">
 <p>
 {\bf Momentum density in the EM fields}
 \[
@@ -1645,7 +1649,7 @@ This is thus simply a conservation law for momentum, with
 <p>
 In a region in which the mechanical momentum is not changing due to external influences, we then have the
 </p>
-<div class="main div" id="orgaafc4b4">
+<div class="main div" id="org94bfc0c">
 <p>
 {\bf Continuity equation for EM momentum}
 \[
@@ -1661,7 +1665,7 @@ In a region in which the mechanical momentum is not changing due to external inf
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce_mst.html b/build/emd_ce_mst.html
index 3c38404..77114e9 100644
--- a/build/emd_ce_mst.html
+++ b/build/emd_ce_mst.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1675,7 +1679,7 @@ and similarly for \({\boldsymbol B}\). We thus get
 <p>
 This expression can be greatly simplified by introducing the
 </p>
-<div class="main div" id="org9016172">
+<div class="main div" id="org516af43">
 <p>
 {\bf Maxwell stress tensor}
 \[
@@ -1698,7 +1702,7 @@ The element \(T_{ij}\) represents the force per unit area in the $i$th direction
 <p>
 We then obtain
 </p>
-<div class="main div" id="org39d7962">
+<div class="main div" id="org38f0a89">
 <p>
 {\bf EM force per unit volume}
 \[
@@ -1710,7 +1714,7 @@ We then obtain
 <p>
 where \({\boldsymbol S}\) is the Poynting vector. Integrating, we obtain the
 </p>
-<div class="main div" id="org384fd10">
+<div class="main div" id="orgf9a42ff">
 <p>
 {\bf Total force on charges in volume}
 \[
@@ -1726,7 +1730,7 @@ where \({\boldsymbol S}\) is the Poynting vector. Integrating, we obtain the
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_ce_poy.html b/build/emd_ce_poy.html
index f3001bb..c49685f 100644
--- a/build/emd_ce_poy.html
+++ b/build/emd_ce_poy.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1687,7 +1691,7 @@ so we get
 Substituting this in \ref{Gr(8.6)} and using the divergence theorem,
 we obtain
 </p>
-<div class="main div" id="org4fee5c1">
+<div class="main div" id="org33b0d12">
 <p>
 {\bf Poynting's theorem}
 \[
@@ -1712,7 +1716,7 @@ energy is carried by EM fields out of \({\cal V}\) across its boundary surface.
 <p>
 Energy per unit time, per unit area carried by EM fields:
 </p>
-<div class="core div" id="org31c447f">
+<div class="core div" id="orgb00d4be">
 <p>
 {\bf Poynting vector}
 \[
@@ -1725,7 +1729,7 @@ Energy per unit time, per unit area carried by EM fields:
 <p>
 We can thus express Poynting's theorem more compactly:
 </p>
-<div class="core div" id="org0a1de2b">
+<div class="core div" id="org618d06c">
 <p>
 {\bf Poynting's theorem}
 \[
@@ -1738,7 +1742,7 @@ We can thus express Poynting's theorem more compactly:
 <p>
 where we have defined the total
 </p>
-<div class="core div" id="org18b8949">
+<div class="core div" id="orgb4f2685">
 <p>
 {\bf Energy in electromagnetic fields}
 \[
@@ -1761,7 +1765,7 @@ Then,
 \]
 so we get the
 </p>
-<div class="core div" id="org3f5d20d">
+<div class="core div" id="org1eaf77c">
 <p>
 {\bf Poynting theorem (differential form)}
 \[
@@ -1778,7 +1782,7 @@ and has a similar for to the continuity equation
 
 
 
-<div class="example div" id="org9d76705">
+<div class="example div" id="org545c704">
 <p>
 \paragraph{Example 8.1}  Current in a wire:  Joule heating.  Energy per unit time delivered to wire:  from Poynting.
 Assuming that the field is uniform, the electric field parallel to the wire is
@@ -1810,7 +1814,7 @@ and the value is as expected.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_emw.html b/build/emd_emw.html
index cbf0db6..153afa1 100644
--- a/build/emd_emw.html
+++ b/build/emd_emw.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emd.emw</span></h3>
 
 <div class="outline-text-3" id="text-emd_emw">
-<details class="prereq" id="orgdd3d3f8">
-<summary id="orgd8f94af">
+<details class="prereq" id="org5bcd123">
+<summary id="org41526cb">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1629,8 +1633,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org8ebd2c8">
-<summary id="org56a0c80">
+<details class="objectives" id="org81e7bec">
+<summary id="org62ac99a">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1658,7 +1662,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_emw_ep.html b/build/emd_emw_ep.html
index 9800bf7..daa05ee 100644
--- a/build/emd_emw_ep.html
+++ b/build/emd_emw_ep.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1649,7 +1653,7 @@ so for a monochromatic EM plan wave,
 \]
 or more succinctly:
 </p>
-<div class="main div" id="org5ab2d39">
+<div class="main div" id="orgeb0be24">
 <p>
 {\bf Poynting vector of a monochromatic EM wave}
 \[
@@ -1665,7 +1669,7 @@ This has a transparent physical interpretation: the energy density \(u\) flows w
 <p>
 Similary, we get the
 </p>
-<div class="main div" id="org703b070">
+<div class="main div" id="org372457d">
 <p>
 {\bf Momentum density of a monochromatic EM wave}
 \[
@@ -1703,7 +1707,7 @@ The {\it radiation pressure} is the momentum transfer per unit area per unit of
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_emw_mpw.html b/build/emd_emw_mpw.html
index 05e00f9..66d80a3 100644
--- a/build/emd_emw_mpw.html
+++ b/build/emd_emw_mpw.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1650,7 +1654,7 @@ B_0 = \frac{k}{\omega} E_0 = \frac{1}{c} E_0.
 Generalizing to propagation in the direction of an arbitrary wavevector
 \({\boldsymbol k}\) and (transverse) polarization vector \(\hat{\boldsymbol n}\), we have the
 </p>
-<div class="core div" id="orgf8f14a8">
+<div class="core div" id="org22a7fdd">
 <p>
 {\bf E and B fields for a monochromatic EM plane wave}
 \[
@@ -1681,7 +1685,7 @@ or if you prefer explicit real parts (adding a possible phase shift \(\delta\)):
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emd_emw_we.html b/build/emd_emw_we.html
index 4b87c7f..83cf2fe 100644
--- a/build/emd_emw_we.html
+++ b/build/emd_emw_we.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1647,7 +1651,7 @@ These take the form of coupled first-order partial differential equations for \(
 Since \({\boldsymbol \nabla} \cdot {\bf E} = 0\) and \({\boldsymbol \nabla} \cdot {\bf B} = 0\),
 we get the
 </p>
-<div class="core div" id="org6e2c86d">
+<div class="core div" id="org1160663">
 <p>
 {\bf Wave equations for electric and magnetic fields in vacuum}
 \[
@@ -1690,7 +1694,7 @@ the actual electric and magnetic fields are given by the real part.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm.html b/build/emdm.html
index 0aacaaf..0b6b77c 100644
--- a/build/emdm.html
+++ b/build/emdm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_Me.html b/build/emdm_Me.html
index 795b7e7..37b1302 100644
--- a/build/emdm_Me.html
+++ b/build/emdm_Me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_Me_Mem.html b/build/emdm_Me_Mem.html
index 419b7f0..c187471 100644
--- a/build/emdm_Me_Mem.html
+++ b/build/emdm_Me_Mem.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1654,7 +1658,7 @@ dI = \frac{\partial \sigma_b}{\partial t} da_{\perp} = \frac{\partial P}{\partia
 \]
 We therefore have the
 </p>
-<div class="core div" id="orgb555ebf">
+<div class="core div" id="orgff46cb4">
 <p>
 {\bf Polarization current density}
 \[
@@ -1672,7 +1676,7 @@ the polarization current is the result of linear motion of charge when
 polarization changes).  We can check consistency with the continuity equation
 associated to the conservation of bound charges:
 </p>
-<aside id="org86c5ff2">
+<aside id="orgbce7d73">
 <p>
 Note the unfortunate labelling: it would have been nicer to have \(\rho_b\) be the charge associated to current
   \({\boldsymbol J}_b\) but this is not the convention used here.
@@ -1695,7 +1699,7 @@ Changing magnetization does not lead to analogous accumulation of charge and cur
 In view of this:  total charge density can be separated into 2 parts,
 {\it free} and {\it bound}:
 </p>
-<div class="main div" id="orgf8c82b2">
+<div class="main div" id="org4df7865">
 <p>
 \[
     \rho = \rho_f + \rho_b = \rho_f - {\boldsymbol \nabla} \cdot {\bf P}
@@ -1708,7 +1712,7 @@ In view of this:  total charge density can be separated into 2 parts,
 and current can be separated into three parts, {\it free}, {\it bound} and
 {\it polarization}:
 </p>
-<div class="main div" id="org4054380">
+<div class="main div" id="orgcc32502">
 <p>
 \[
   {\bf J} = {\bf J}_f + {\bf J}_b + {\bf J}_p = {\bf J}_f + {\boldsymbol ∇} × {\bf M}
@@ -1732,7 +1736,7 @@ Gauss's law:  can be rewritten
 \]
 where (as in static case)
 </p>
-<div class="core div" id="orgf78b92c">
+<div class="core div" id="org7600f00">
 <p>
 \[
     {\bf D} \equiv \varepsilon_0 {\bf E} + {\bf P}
@@ -1758,7 +1762,7 @@ or
 \]
 where as before
 </p>
-<div class="core div" id="org513c514">
+<div class="core div" id="orgb942ad8">
 <p>
 \[
     {\bf H} \equiv \frac{1}{\mu_0} {\bf B} - {\bf M}
@@ -1776,7 +1780,7 @@ bound parts, since they don't involve \(\rho\) or \({\bf J}\).
 <p>
 In terms of free charges and currents, we thus get
 </p>
-<div class="core div" id="org686ea33">
+<div class="core div" id="orgd9d30d5">
 <p>
 {\bf Maxwell's equations {\it (in matter)}}
 </p>
@@ -1802,7 +1806,7 @@ Must be complemented by the {\bf constitutive relations} giving \({\bf D}\) and
 in terms of \({\bf E}\) and \({\bf B}\).
 For the restricted case of linear media:
 </p>
-<div class="main div" id="org6accc1d">
+<div class="main div" id="orge1df28e">
 <p>
 \[
     {\bf P} = \varepsilon_0 \chi_e {\bf E}, \hspace{1cm}
@@ -1826,7 +1830,7 @@ where \(\varepsilon \equiv \varepsilon_0(1 + \chi_e)\) and \(\mu \equiv \mu_0 (1
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_Me_bc.html b/build/emdm_Me_bc.html
index 568d67f..d03e4cd 100644
--- a/build/emdm_Me_bc.html
+++ b/build/emdm_Me_bc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 Discontinuities between different media, deduced from
 </p>
-<div class="core div" id="org18c9c85">
+<div class="core div" id="orgbbf71a6">
 <p>
 {\bf Maxwell's equations {\it (in matter)}, integral form}
 </p>
@@ -1699,7 +1703,7 @@ These are basis of theory of reflection and refraction.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm.html b/build/emdm_emwm.html
index a018a56..475343d 100644
--- a/build/emdm_emwm.html
+++ b/build/emdm_emwm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1633,7 +1637,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_ad.html b/build/emdm_emwm_ad.html
index e399491..e57d9a6 100644
--- a/build/emdm_emwm_ad.html
+++ b/build/emdm_emwm_ad.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_ad_c.html b/build/emdm_emwm_ad_c.html
index e146c1e..b123a4a 100644
--- a/build/emdm_emwm_ad_c.html
+++ b/build/emdm_emwm_ad_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1725,7 +1729,7 @@ so the final form of the fields is
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_plm.html b/build/emdm_emwm_plm.html
index fc057dc..60f74b8 100644
--- a/build/emdm_emwm_plm.html
+++ b/build/emdm_emwm_plm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1656,7 +1660,7 @@ v = \frac{1}{\sqrt{\mu \varepsilon}} = \frac{c}{n}
 \]
 where the index of refraction of the material is defined as
 </p>
-<div class="main div" id="orgc00345d">
+<div class="main div" id="orgeaea7cb">
 <p>
 {\bf Index of refraction}
 \[
@@ -1700,7 +1704,7 @@ I = \frac{1}{2} \varepsilon v E_0^2
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refl.html b/build/emdm_emwm_refl.html
index 11168d5..9e5e440 100644
--- a/build/emdm_emwm_refl.html
+++ b/build/emdm_emwm_refl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1644,7 +1648,7 @@ Detailed study:  starts from boundary conditions \ref{Gr(7.64)},
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refl_Ba.html b/build/emdm_emwm_refl_Ba.html
index 31d787f..9e0877f 100644
--- a/build/emdm_emwm_refl_Ba.html
+++ b/build/emdm_emwm_refl_Ba.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,7 +1628,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refl_Fe.html b/build/emdm_emwm_refl_Fe.html
index 93fc096..f9cb780 100644
--- a/build/emdm_emwm_refl_Fe.html
+++ b/build/emdm_emwm_refl_Fe.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,7 +1629,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refl_ni.html b/build/emdm_emwm_refl_ni.html
index 6704f16..f80c523 100644
--- a/build/emdm_emwm_refl_ni.html
+++ b/build/emdm_emwm_refl_ni.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1716,7 +1720,7 @@ R + T = 1.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refl_oi.html b/build/emdm_emwm_refl_oi.html
index 5de1296..6978b35 100644
--- a/build/emdm_emwm_refl_oi.html
+++ b/build/emdm_emwm_refl_oi.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1656,7 +1660,7 @@ These forms for incident, reflected and transmitted wave can be substituted in t
 <p>
 From now on we will orient the axes so that \({\boldsymbol k}_I\) lies in the \(xz\) plane. This means that \({\boldsymbol k}_R\) and \({\boldsymbol k}_T\) also lie in that plane. This is the
 </p>
-<div class="core div" id="orgefbfc7d">
+<div class="core div" id="orga1858e0">
 <p>
 {\bf First law of reflection:}
 the incident, reflected and transmitted wave vectors form a plane (called the plane of incidence) which also includes the normal to the surface.
@@ -1671,7 +1675,7 @@ Specializing (\ref{eq:RTObliquek}) to our notations, we have
 with the incidence (\(\theta_I\)) and reflection (\(\theta_R\)) angles
 and the angle of refraction (\(\theta_T\)) obey the following laws:
 </p>
-<div class="core div" id="org13fc947">
+<div class="core div" id="orgc1aaaad">
 <p>
 {\bf Law of reflection}
 \[
@@ -1729,7 +1733,7 @@ while the third equation becomes
 \]
 Writing everything in terms of the incident amplitude, we get
 </p>
-<div class="main div" id="orgd7a540b">
+<div class="main div" id="org4da7748">
 <p>
 {\bf Fresnel's equations for reflection and transmission amplitudes (parallel case)}
 \[
@@ -1749,7 +1753,7 @@ Amplitudes for transmitted and reflected wave: depend on angle of incidence:
 Behaviour: for \(\theta_I = 0\) we recover (\ref{Gr(9.82)}).
 For grazing waves \(\theta_I \rightarrow \pi/2\) we have that \(\alpha \rightarrow \infty\) and the wave is totally reflected. The most interesting angle is the one at which \(\alpha = \beta\) and the reflected wave has zero amplitude. This is known as
 </p>
-<div class="main div" id="orgdb6468b">
+<div class="main div" id="orge2d9787">
 <p>
 {\bf Brewster's angle {\it (at which the reflected wave amplitude vanishes)}}
   \[
@@ -1786,7 +1790,7 @@ Of course, we get \(R + T = 1\) as expected.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_refr.html b/build/emdm_emwm_refr.html
index afe5bcd..d4dfc1a 100644
--- a/build/emdm_emwm_refr.html
+++ b/build/emdm_emwm_refr.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,7 +1629,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_wg.html b/build/emdm_emwm_wg.html
index e54021d..4e9dca9 100644
--- a/build/emdm_emwm_wg.html
+++ b/build/emdm_emwm_wg.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_wg_c.html b/build/emdm_emwm_wg_c.html
index 769e6a5..11b5e98 100644
--- a/build/emdm_emwm_wg_c.html
+++ b/build/emdm_emwm_wg_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1651,7 +1655,7 @@ where \(A\) is a constant amplitude. Substituting and taking the real part,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_wg_gw.html b/build/emdm_emwm_wg_gw.html
index 99ed1cd..4a18f02 100644
--- a/build/emdm_emwm_wg_gw.html
+++ b/build/emdm_emwm_wg_gw.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1675,7 +1679,7 @@ with an identical equation for \(B_z\). If \(E_z = 0\) the waves are called {\bf
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emdm_emwm_wg_r.html b/build/emdm_emwm_wg_r.html
index 3e89e1e..80d9f13 100644
--- a/build/emdm_emwm_wg_r.html
+++ b/build/emdm_emwm_wg_r.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1684,7 +1688,7 @@ which is {\it greater} than \(c\). The energy of the wave however propagates at
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emf.html b/build/emf.html
index 0426e48..11cd62a 100644
--- a/build/emf.html
+++ b/build/emf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emf</span></h2>
 
 <div class="outline-text-2" id="text-emf">
-<details class="prereq" id="org0b4147b">
-<summary id="orgaa9a8c2">
+<details class="prereq" id="org86ffe7e">
+<summary id="org72ae362">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1628,8 +1632,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="orgd0127b4">
-<summary id="orgf210d58">
+<details class="objectives" id="org9d4a979">
+<summary id="org984c0c5">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1652,7 +1656,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emf_g.html b/build/emf_g.html
index 411720f..4ad60e8 100644
--- a/build/emf_g.html
+++ b/build/emf_g.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1649,7 +1653,7 @@ implementing a <b>gauge transformation</b>.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emf_g_Cg.html b/build/emf_g_Cg.html
index 2472f08..d4b32e6 100644
--- a/build/emf_g_Cg.html
+++ b/build/emf_g_Cg.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1648,7 +1652,7 @@ Although Gauss's law looks nice in the Coulomb gauge, Amp{\`e}re-Maxwell does no
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emf_g_Lg.html b/build/emf_g_Lg.html
index 618124c..6a97b4f 100644
--- a/build/emf_g_Lg.html
+++ b/build/emf_g_Lg.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1634,7 +1638,7 @@ while the equation for \(V\) becomes
 \]
 These can be written compactly upon introducing a new operator: the
 </p>
-<div class="core div" id="orgd5ba96e">
+<div class="core div" id="orgd4a4d0b">
 <p>
 {\bf d'Alembertian operator}
 \[
@@ -1647,7 +1651,7 @@ These can be written compactly upon introducing a new operator: the
 <p>
 so we get the
 </p>
-<div class="core div" id="org15005e7">
+<div class="core div" id="orgbeb1250">
 <p>
 {\bf Inhomogeneous Maxwell equations (Lorenz gauge)}
 \[
@@ -1684,7 +1688,7 @@ we have by direct inspection
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emf_svp.html b/build/emf_svp.html
index c8426c6..e18ec94 100644
--- a/build/emf_svp.html
+++ b/build/emf_svp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1635,7 +1639,7 @@ Useful strategy: represent fields in terms of potentials.
 <p>
 Easiest:
 </p>
-<div class="core div" id="org389d31f">
+<div class="core div" id="org45e0ed0">
 <p>
 \[
     {\boldsymbol B} = {\boldsymbol \nabla} \times {\boldsymbol A}
@@ -1651,7 +1655,7 @@ Putting this into Faraday's law gives
 \]
 so this can be written as the gradient of a scalar (by choice: \(-{\boldsymbol \nabla} V\)) so we get
 </p>
-<div class="core div" id="orgbbcf54f">
+<div class="core div" id="orgb9810af">
 <p>
 \[
     {\boldsymbol E} = -{\boldsymbol \nabla} V - \frac{\partial {\boldsymbol A}}{\partial t}
@@ -1664,7 +1668,7 @@ so this can be written as the gradient of a scalar (by choice: \(-{\boldsymbol \
 <p>
 Using this potential representation for \({\boldsymbol E}\) and \({\boldsymbol B}\) automatically fulfills the two homogeneous Maxwell equations. For the inhomogeneous equations, substituting (\ref{eq:E_from_Potentials}) into Gauss's law gives
 </p>
-<div class="main div" id="org2d36baf">
+<div class="main div" id="org1c236f0">
 <p>
 \[
     {\boldsymbol \nabla}^2 V + \frac{\partial}{\partial t} {\boldsymbol \nabla} \cdot {\boldsymbol A} = -\frac{\rho}{\varepsilon_0}
@@ -1680,7 +1684,7 @@ whereas Amp{\`ere}-Maxwell becomes
 \]
 which becomes after simple rearrangement and use of the identity \({\boldsymbol \nabla} \times \left({\boldsymbol \nabla} \times {\boldsymbol A}\right) = {\boldsymbol \nabla} ({\boldsymbol \nabla} \cdot {\boldsymbol A}) - {\boldsymbol \nabla}^2 {\boldsymbol A}\),
 </p>
-<div class="main div" id="orga7cdd8b">
+<div class="main div" id="orgf3f4dcd">
 <p>
 \[
   \left( {\boldsymbol ∇}^2 {\boldsymbol A} - μ_0 ε_0 \frac{∂^2 {\boldsymbol A}}{∂ t^2} \right)
@@ -1703,7 +1707,7 @@ which becomes after simple rearrangement and use of the identity \({\boldsymbol
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems.html b/build/ems.html
index 5fadee2..b87a0be 100644
--- a/build/ems.html
+++ b/build/ems.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca.html b/build/ems_ca.html
index 048e882..778edb1 100644
--- a/build/ems_ca.html
+++ b/build/ems_ca.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">ems.ca</span></h3>
 
 <div class="outline-text-3" id="text-ems_ca">
-<details class="prereq" id="org9f1c7db">
-<summary id="orgbf053b0">
+<details class="prereq" id="orgbb80f83">
+<summary id="org379b6a1">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1628,8 +1632,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org06b35e7">
-<summary id="org6416a57">
+<details class="objectives" id="orgd1100e2">
+<summary id="org27953b9">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1654,7 +1658,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_fe.html b/build/ems_ca_fe.html
index b3f4569..56ae20a 100644
--- a/build/ems_ca_fe.html
+++ b/build/ems_ca_fe.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,7 +1628,7 @@ A generic configuration of static charges coupled via the Coulomb interaction
 defines an electrostatic problem, whose solution is in principle obtained
 from calculating either the field according to <a href="./ems_es_ef_ccd.html#E_vcd">E_vcd</a>
 </p>
-<div class="main div" id="orgb912407">
+<div class="main div" id="org14f8ad7">
 \begin{equation*}
   {\bf E} ({\bf r}) = \frac{1}{4\pi\varepsilon_0} \int_{\mathbb{R}^3} d\tau' \rho({\bf r}') \frac{{\bf r} - {\bf r}'}{|{\bf r} - {\bf r}'|^3}
 \end{equation*}
@@ -1634,7 +1638,7 @@ from calculating either the field according to <a href="./ems_es_ef_ccd.html#E_v
 or (often simpler) by calculating the electrostatic potential, using either the
 explicit construction (\ref{eq:V_from_rho})
 </p>
-<div class="main div" id="orgc09a05f">
+<div class="main div" id="org83b53d5">
 <p>
 \[
     V({\bf r}) = \frac{1}{4\pi \varepsilon_0} \int_{\mathbb{R}^3} d\tau' \frac{\rho({\bf r}')}{|{\bf r} - {\bf r}'|}.
@@ -1650,7 +1654,7 @@ condition (\ref{Gr(2.20)}) can be expressed as the single
 'local' (differential) condition (Poisson's equation) (\ref{eq:Poisson})
 </p>
 
-<div class="core div" id="orgbe52068">
+<div class="core div" id="org52d8655">
 <p>
 \[
     {\boldsymbol \nabla}^2 V = -\frac{\rho}{\varepsilon_0}.
@@ -1664,7 +1668,7 @@ condition (\ref{Gr(2.20)}) can be expressed as the single
 In the specific case where the charge density vanishes, we fall back onto the simpler
 Laplace equation
 </p>
-<div class="core div" id="orgb4303af">
+<div class="core div" id="orgceb6a79">
 <p>
 \[
     {\boldsymbol \nabla}^2 V = 0
@@ -1686,7 +1690,7 @@ Laplace equation
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_fe_L.html b/build/ems_ca_fe_L.html
index 2d69409..90204c6 100644
--- a/build/ems_ca_fe_L.html
+++ b/build/ems_ca_fe_L.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1698,7 +1702,7 @@ are necessarily positive, we thus require \(f_x &gt; 0\), \(f_y &gt; 0\) and \(f
 of the \(f_x + f_y + f_z = 0\) condition above.
 </p>
 
-<div class="info div" id="orga2b5411">
+<div class="info div" id="org12caa26">
 <p>
 <b>Earnshaw's theorem</b> <br>
 Since solutions to Laplace's equation have no local minimum,
@@ -1788,7 +1792,7 @@ This all feels a bit amateurish and not very systematic. Can we be more precise
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_fe_g.html b/build/ems_ca_fe_g.html
index 4151443..fb81d48 100644
--- a/build/ems_ca_fe_g.html
+++ b/build/ems_ca_fe_g.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,11 +1622,11 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">ems.ca.fe.g</span></h5>
 <div class="outline-text-5" id="text-ems_ca_fe_g">
-<div class="info div" id="orgbc8a544">
+<div class="info div" id="org8d7045e">
 <p>
 <b>George Green</b>
 </p>
-<aside id="org5513bf5">
+<aside id="org53725f0">
 <p>
 See a \href{short biography of George Green on Wikipedia}{https://en.wikipedia.org/wiki/George\_Green\_(mathematician)}.
 </p>
@@ -1676,7 +1680,7 @@ interchanged, and subtract the result, we obtain another useful result known as
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_fe_uP.html b/build/ems_ca_fe_uP.html
index 18392c3..6fd2193 100644
--- a/build/ems_ca_fe_uP.html
+++ b/build/ems_ca_fe_uP.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1648,7 +1652,7 @@ is unique.  For Neumann, the solution is unique apart from an unimportant consta
 <p>
 We can thus finally state the
 </p>
-<div class="core div" id="org0d6841f">
+<div class="core div" id="org6cadf17">
 <p>
 <b>Uniqueness Theorem</b>
 </p>
@@ -1708,7 +1712,7 @@ equipotentials, and capacitance relates the charge to the potential.
 }
 </p>
 
-<div class="info div" id="org05813c2">
+<div class="info div" id="orgca9fd66">
 <p>
 {\bf Comment/warning: {\color{blue} uniqueness theorem on uniqueness theorems}}<br>
 Do not be misled by Griffiths: there is a {\it unique} uniqueness theorem for the
@@ -1722,7 +1726,7 @@ solution of Poisson's equation, namely the one we have stated starting from Gree
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me.html b/build/ems_ca_me.html
index 159795b..ec9c0f9 100644
--- a/build/ems_ca_me.html
+++ b/build/ems_ca_me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1633,7 +1637,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me_Ed.html b/build/ems_ca_me_Ed.html
index cdbfee2..5325641 100644
--- a/build/ems_ca_me_Ed.html
+++ b/build/ems_ca_me_Ed.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1652,7 +1656,7 @@ or in a better coordinate-free form
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me_Eq.html b/build/ems_ca_me_Eq.html
index 9027a19..3f5a4b6 100644
--- a/build/ems_ca_me_Eq.html
+++ b/build/ems_ca_me_Eq.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me_a.html b/build/ems_ca_me_a.html
index ab6343f..9aebf45 100644
--- a/build/ems_ca_me_a.html
+++ b/build/ems_ca_me_a.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1695,7 +1699,7 @@ V({\bf r}) \simeq \frac{1}{4\pi \varepsilon_0} \frac{q d \cos \theta}{r^2}
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me_h.html b/build/ems_ca_me_h.html
index 1f545cc..170c1ed 100644
--- a/build/ems_ca_me_h.html
+++ b/build/ems_ca_me_h.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1626,7 +1630,7 @@ V_{\mbox{\tiny quad}} ({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{1}{r^3} \in
 \]
 and can be rewritten as
 </p>
-<div class="main div" id="orgd014e56">
+<div class="main div" id="org7b16036">
 <p>
 \[
     V_{\mbox{\tiny quad}} ({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{1}{2} \sum_{a,b} \frac{r_a r_b}{r^5} Q_{ab}
@@ -1637,7 +1641,7 @@ and can be rewritten as
 <p>
 in terms of the {\bf quadrupole moment}
 </p>
-<div class="main div" id="org6f7878a">
+<div class="main div" id="orga1ea430">
 <p>
 \[
     Q_{ab} = \int_{\cal V} d\tau_s (3 r_{s,a} r_{s,b} - r_s^2 \delta_{a,b}) \rho ({\bf r}_s).
@@ -1655,7 +1659,7 @@ Moreover, it is traceless, \(\sum_a Q_{aa} = 0\).  It therefore has \(5\) indepe
 <p>
 Our expansion for the potential thus looks like
 </p>
-<div class="main div" id="org64a7b16">
+<div class="main div" id="org1059aa3">
 <p>
 \[
     V({\bf r}) = \frac{1}{4\pi \varepsilon_0} \left( \frac{Q}{r} + \sum_a \frac{r_a}{r^3} p_a + \frac{1}{2} \sum_{a,b} \frac{r_a r_b}{r^5} Q_{ab} + ... \right)
@@ -1674,7 +1678,7 @@ the leading nonvanishing multipole moment is independent of the chosen location
 the origin of the coordinate system (see Jackson Prob. 4.4).
 </p>
 
-<div class="info div" id="org9ec7af8">
+<div class="info div" id="org778fe8a">
 <p>
 {\bf A consistent nomenclature for the multipole expansion?}\\\\
 You all know the terms {\bf monopole}, {\bf dipole} and {\bf quadrupole},
@@ -1733,7 +1737,7 @@ more terms than you might ever (hopefully) need:<br>
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_me_md.html b/build/ems_ca_me_md.html
index f00117c..891459b 100644
--- a/build/ems_ca_me_md.html
+++ b/build/ems_ca_me_md.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,7 +1626,7 @@ Table of contents
 The series (\ref{Gr(3.95)}) is organized in increasing powers of inverse distance.
 The leading term is called the {\bf monopole} term, and is
 </p>
-<div class="core div" id="orgf53b7da">
+<div class="core div" id="org58c7e21">
 <p>
 \[
     V_{\mbox{\tiny mono}} ({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{Q}{r}, \hspace{1cm}
@@ -1643,7 +1647,7 @@ V_{\mbox{\tiny di}} ({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{1}{r^2} \int_
 \]
 This can be written
 </p>
-<div class="core div" id="orgd2594e3">
+<div class="core div" id="org3d8a1b7">
 <p>
 \[
     V_{\mbox{\tiny di}} ({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{\hat{\bf r} \cdot {\bf p}}{r^2},
@@ -1674,7 +1678,7 @@ Since dipole moments are vectors, they are summed following vector addition rule
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_mi.html b/build/ems_ca_mi.html
index b1b0932..13fc45d 100644
--- a/build/ems_ca_mi.html
+++ b/build/ems_ca_mi.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1667,7 +1671,7 @@ In the Image problem, we might want to know what the induced surface charge is.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_mi_fe.html b/build/ems_ca_mi_fe.html
index 9bb1b04..57cc1a3 100644
--- a/build/ems_ca_mi_fe.html
+++ b/build/ems_ca_mi_fe.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1644,7 +1648,7 @@ Half:  \(E^2\) integrated over half the space in (\ref{eq:Energy_as_int_E2}).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_mi_isc.html b/build/ems_ca_mi_isc.html
index e3522dd..1b8e885 100644
--- a/build/ems_ca_mi_isc.html
+++ b/build/ems_ca_mi_isc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1639,7 +1643,7 @@ Q = \int_0^{2\pi} d\phi \int_0^{\infty} dr r \frac{-qd}{2\pi (r^2 + d^2)^{3/2}}
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_mi_o.html b/build/ems_ca_mi_o.html
index 8825c8e..9f4bbac 100644
--- a/build/ems_ca_mi_o.html
+++ b/build/ems_ca_mi_o.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1654,7 +1658,7 @@ whose solution is \(a = d[1 + \alpha]\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_sv.html b/build/ems_ca_sv.html
index 49753cc..c31f85a 100644
--- a/build/ems_ca_sv.html
+++ b/build/ems_ca_sv.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1636,7 +1640,7 @@ some symmetry of the problem to greatly simplify the form of solution to Laplace
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_sv_car.html b/build/ems_ca_sv_car.html
index 839bb70..9c700d5 100644
--- a/build/ems_ca_sv_car.html
+++ b/build/ems_ca_sv_car.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,7 +1622,7 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">ems.ca.sv.car</span></h5>
 <div class="outline-text-5" id="text-ems_ca_sv_car">
-<div class="example div" id="orgb348b87">
+<div class="example div" id="org30edbf0">
 <p>
 {\bf Example: separation of variables (Cartesian coordinates)}<br>
 Two infinite grounded metal plates parallel to the \(xz\) plane, one at \(y = 0\) and the
@@ -1719,7 +1723,7 @@ V(x,y) = \frac{4V_0}{\pi}\sum_{n=1, 3, 5, ...}^{\infty} \frac{1}{n} e^{-n\pi x/a
 </p>
 
 
-<div class="example div" id="orgca275f4">
+<div class="example div" id="org276be97">
 <p>
   {\bf Example: rectangular pipe}<br>
   Two infinitely long grounded plates at \(y = 0,a\) are connected at \(x = \pm b\)
@@ -1764,7 +1768,7 @@ V(x,y) = \frac{4V_0}{\pi} \sum_{n = 1, 3, 5, ...} \frac{1}{n} \frac{\cosh (n\pi
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_sv_cyl.html b/build/ems_ca_sv_cyl.html
index 99a07ec..f937a78 100644
--- a/build/ems_ca_sv_cyl.html
+++ b/build/ems_ca_sv_cyl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,7 +1629,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ca_sv_sph.html b/build/ems_ca_sv_sph.html
index 140c332..903feb8 100644
--- a/build/ems_ca_sv_sph.html
+++ b/build/ems_ca_sv_sph.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 In spherical coordinates, the Laplace equation takes the following form:
 </p>
-<div class="main div" id="org402edd2">
+<div class="main div" id="orgaeaaca3">
 <p>
 
 </p>
@@ -1782,7 +1786,7 @@ Ex.:  second solution for \(l = 0\) is
 <p>
 General solution to problem with azimuthal symmetry:
 </p>
-<div class="main div" id="org50e2233">
+<div class="main div" id="orgd189af6">
 <p>
 \[
     V(r,\theta) = \sum_{l=0}^{\infty} \left( A_l r^l + \frac{B_l}{r^{l+1}} \right) P_l (\cos \theta)
@@ -1794,7 +1798,7 @@ General solution to problem with azimuthal symmetry:
 
 
 
-<div class="example div" id="org7c85b31">
+<div class="example div" id="orgcc658e8">
 <p>
 <b>Example: separation of variables (spherical coordinates)</b>
 </p>
@@ -1886,7 +1890,7 @@ V(r, \theta) = \frac{k}{2} (1 - \frac{r}{R} \cos \theta).
 </p>
 
 
-<div class="example div" id="orgc394feb">
+<div class="example div" id="org650a799">
 <p>
 <b>Example: surface charge density on sphere</b>
 </p>
@@ -2004,7 +2008,7 @@ V^&gt; (r, \theta) = \frac{k R^3}{3\varepsilon_0} \frac{\cos \theta}{r^2} \hspac
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es.html b/build/ems_es.html
index 37c2a1f..88a5946 100644
--- a/build/ems_es.html
+++ b/build/ems_es.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,8 +1629,8 @@ Table of contents
 <li>PM 1</li>
 </ul>
 
-<details class="prereq" id="org2b3a5fa">
-<summary id="orgfaa4637">
+<details class="prereq" id="org413eb9a">
+<summary id="orgecc6691">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1634,8 +1638,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="orgf491799">
-<summary id="org7cfa128">
+<details class="objectives" id="org326aeea">
+<summary id="org45511dc">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1664,7 +1668,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_c.html b/build/ems_es_c.html
index f2e9557..86441be 100644
--- a/build/ems_es_c.html
+++ b/build/ems_es_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1637,7 +1641,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_c_cap.html b/build/ems_es_c_cap.html
index 75cb852..4ad25b2 100644
--- a/build/ems_es_c_cap.html
+++ b/build/ems_es_c_cap.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1640,7 +1644,7 @@ C \equiv \frac{Q}{V}
 \]
 </p>
 
-<div class="example div" id="org873e6f7">
+<div class="example div" id="orgccf6af5">
 <p>
 <b>Example 2.11</b>:
 find the capacitance of two concentric spherical metallic shells with radii \(a\) and \(b\).
@@ -1670,7 +1674,7 @@ W = \frac{1}{2} C V^2
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_c_ic.html b/build/ems_es_c_ic.html
index b4222b6..f168f59 100644
--- a/build/ems_es_c_ic.html
+++ b/build/ems_es_c_ic.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1623,7 +1627,7 @@ Charge in hollow conductor.
 Induced surface charges on inside and outside surfaces.
 </p>
 
-<div class="example div" id="org08ed9bf">
+<div class="example div" id="org97b5c49">
 <p>
 <b>Example 2.9</b>:  field outside a spherical conductor centered at origin, having
 a cavity of a weird shape with a point charge \(q\) somewhere inside.  What is the field
@@ -1648,7 +1652,7 @@ remains neutral, so a charge \(q\) distributes itself uniformly over its externa
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_c_p.html b/build/ems_es_c_p.html
index ed6dccf..17f08fa 100644
--- a/build/ems_es_c_p.html
+++ b/build/ems_es_c_p.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,7 +1622,7 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">ems.es.c.p</span></h5>
 <div class="outline-text-5" id="text-ems_es_c_p">
-<div class="main div" id="org2f459a7">
+<div class="main div" id="org1f95aef">
 <p>
 <b>Basic Properties of a Conductor</b>
 </p>
@@ -1646,7 +1650,7 @@ for a system of conductors held at fixed potentials, the solution is unique.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_c_sc.html b/build/ems_es_c_sc.html
index 9fcfe8b..da0ec47 100644
--- a/build/ems_es_c_sc.html
+++ b/build/ems_es_c_sc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1656,7 +1660,7 @@ which can also be obtained from the principle of virtual work.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_e.html b/build/ems_es_e.html
index 4fd268f..733a2c8 100644
--- a/build/ems_es_e.html
+++ b/build/ems_es_e.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1653,7 +1657,7 @@ W_u = -\int_{{\bf a}}^{{\bf b}} {\bf E} \cdot d{\bf l}
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_e_c.html b/build/ems_es_e_c.html
index c9b8665..1da74a7 100644
--- a/build/ems_es_e_c.html
+++ b/build/ems_es_e_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Radiation theory points to the preferable interpretation that the energy is stor
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_e_ccd.html b/build/ems_es_e_ccd.html
index 7f61ddd..917551b 100644
--- a/build/ems_es_e_ccd.html
+++ b/build/ems_es_e_ccd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1655,7 +1659,7 @@ W = \frac{\varepsilon_0}{2} \left( \int_{\cal V} E^2 d\tau + \oint_{\cal S} V {\
 <p>
 Integrating over all space,
 </p>
-<div class="core div" id="org0f826c0">
+<div class="core div" id="org22ea2cf">
 <p>
 
 </p>
@@ -1669,7 +1673,7 @@ Integrating over all space,
 
 </div>
 
-<div class="example div" id="orgefdb634">
+<div class="example div" id="org05197ef">
 <p>
 <b>Example 2.8</b>:  Find the energy of a uniformly charged spherical shell of total charge \(q\) and radius \(R\).
 </p>
@@ -1720,7 +1724,7 @@ so
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_e_pcd.html b/build/ems_es_e_pcd.html
index dc54212..8fce649 100644
--- a/build/ems_es_e_pcd.html
+++ b/build/ems_es_e_pcd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1636,7 +1640,7 @@ W = \frac{1}{2} \sum_{i=1}^m q_i V({\bf r}_i)
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ec.html b/build/ems_es_ec.html
index 671a5ce..da661d9 100644
--- a/build/ems_es_ec.html
+++ b/build/ems_es_ec.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
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-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1637,7 +1641,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ec_b.html b/build/ems_es_ec_b.html
index 77635ac..b0fcaed 100644
--- a/build/ems_es_ec_b.html
+++ b/build/ems_es_ec_b.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,7 +1632,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ec_c.html b/build/ems_es_ec_c.html
index 3427ab9..1c9973b 100644
--- a/build/ems_es_ec_c.html
+++ b/build/ems_es_ec_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,7 +1632,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ec_q.html b/build/ems_es_ec_q.html
index b2ad103..a07d111 100644
--- a/build/ems_es_ec_q.html
+++ b/build/ems_es_ec_q.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,7 +1632,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ec_s.html b/build/ems_es_ec_s.html
index 5ebd06d..5905536 100644
--- a/build/ems_es_ec_s.html
+++ b/build/ems_es_ec_s.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1627,7 +1631,7 @@ Point charges: reality or idealization?
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ef.html b/build/ems_es_ef.html
index 64069a8..4482b80 100644
--- a/build/ems_es_ef.html
+++ b/build/ems_es_ef.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1637,7 +1641,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ef_Gl.html b/build/ems_es_ef_Gl.html
index 794ed27..3135bed 100644
--- a/build/ems_es_ef_Gl.html
+++ b/build/ems_es_ef_Gl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1663,14 +1667,14 @@ sphere of radius \(r\) around the charge,
 <p>
 so by superposition, we obtain
 </p>
-<div class="eqlabel" id="org567fae3">
+<div class="eqlabel" id="org804902c">
 <p>
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-<div class="alteqlabels" id="orgd08d994">
+<div class="alteqlabels" id="org04a2212">
 <ul class="org-ul">
 <li>Gr (2.13)</li>
 </ul>
@@ -1678,7 +1682,7 @@ so by superposition, we obtain
 </div>
 
 </div>
-<div class="core div" id="org107f70e">
+<div class="core div" id="orgbbc9bc1">
 <p>
 <b>Gauss' law (in integral form)</b>
 </p>
@@ -1710,14 +1714,14 @@ By applying the divergence theorem,
 and using \(Q_{\mbox{enc}} = \int_{\cal V} \rho d\tau\),  and using the fact the the choice of volume
 is arbitrary, we get
 </p>
-<div class="eqlabel" id="orgcbc0cba">
+<div class="eqlabel" id="org06ff080">
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 <a id="Gl_d"></a><a href="./ems_es_ef_Gl.html#Gl_d"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org4033327">
+<div class="alteqlabels" id="orgcf50b9d">
 <ul class="org-ul">
 <li>Gr (2.14)</li>
 </ul>
@@ -1725,7 +1729,7 @@ is arbitrary, we get
 </div>
 
 </div>
-<div class="core div" id="orgb66b8f3">
+<div class="core div" id="orgf131b44">
 <p>
 <b>Gauss' law in differential form</b>
 </p>
@@ -1755,7 +1759,7 @@ Using <a href="./c_m_dd_3d.html#divdel">divdel</a>,
 
 <p>
 \[
-{\boldsymbol \nabla} \cdot {\bf E} = \frac{1}{4\pi \varepsilon_0} \int d\tau' \rho({\bf r}') 4\pi \delta ({\bf r} - {\bf r}') = \frac{\rho({\bf r})}{\varepsilon_0}
+{\boldsymbol \nabla} \cdot {\bf E} = \frac{1}{4\pi \varepsilon_0} \int d\tau' \rho({\bf r}') ~4\pi \delta ({\bf r} - {\bf r}') = \frac{\rho({\bf r})}{\varepsilon_0}
 \label{Gr(2.16)}
 \]
 </p>
@@ -1784,7 +1788,7 @@ cylindrical or plane symmetry.
 Gaussian surfaces:  respectively, concentric sphere, coaxial cylinder, pillbox.
 </p>
 
-<div class="example div" id="org34f5bc3">
+<div class="example div" id="org57bb4a4">
 <p>
 <b>Example 2.2</b>:  Field outside a uniformly charged sphere of radius \(R\) and total charge \(q\).
 </p>
@@ -1815,7 +1819,7 @@ Same as point charge at origin!
 
 </div>
 
-<div class="example div" id="org588cdee">
+<div class="example div" id="orgc83260f">
 <p>
 <b>Example 2.3</b>:  infinitely long cylinder carrying charge density \(\rho = k s\) for some constant \(k\). Find \({\bf E}\) within the cylinder.
 </p>
@@ -1854,7 +1858,7 @@ Therefore,
 </div>
 
 
-<div class="example div" id="orgd319ae5">
+<div class="example div" id="orgabb478b">
 <p>
 <b>Example 2.4</b>:  infinite plane (defined by \(z = 0\)) with uniform surface charge density \(\sigma\).  Find \({\bf E}\).
 </p>
@@ -1880,7 +1884,7 @@ where \(\hat{\bf n}\) is a unit vector extending away from the plane.  Independe
 
 </div>
 
-<div class="example div" id="org65c3abd">
+<div class="example div" id="orgd7a4c2f">
 <p>
 <b>Example 2.5</b>: two infinite planes (put them vertical) carrying equal but opposite uniform surface charge densities \(\pm \sigma\).
 </p>
@@ -1897,7 +1901,7 @@ where \(\hat{\bf n}\) is a unit vector extending away from the plane.  Independe
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ef_cE.html b/build/ems_es_ef_cE.html
index bd1b924..d2fceba 100644
--- a/build/ems_es_ef_cE.html
+++ b/build/ems_es_ef_cE.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,14 +1626,14 @@ Table of contents
 Since the work done when moving on a closed path vanishes, we have
 </p>
 
-<div class="eqlabel" id="org1d40bf9">
+<div class="eqlabel" id="orga7e79ce">
 <p>
 <a id="ointE0"></a><a href="./ems_es_ef_cE.html#ointE0"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org3f966a4">
+<div class="alteqlabels" id="org8ebbbb3">
 <ul class="org-ul">
 <li>Gr (2.19)</li>
 </ul>
@@ -1637,7 +1641,7 @@ Since the work done when moving on a closed path vanishes, we have
 </div>
 
 </div>
-<div class="core div" id="org78f117c">
+<div class="core div" id="orgf093675">
 <p>
 
 </p>
@@ -1655,14 +1659,14 @@ Since the work done when moving on a closed path vanishes, we have
 which by <a href="./c_m_ic_stokes.html#Stokes">Stokes' theorem</a> implies that the electrostatic field is curlless,
 </p>
 
-<div class="eqlabel" id="org19a8fe3">
+<div class="eqlabel" id="org616e452">
 <p>
 <a id="curlE0"></a><a href="./ems_es_ef_cE.html#curlE0"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="orgf412ad8">
+<div class="alteqlabels" id="orgc32cca9">
 <ul class="org-ul">
 <li>Gr (2.20)</li>
 </ul>
@@ -1670,7 +1674,7 @@ which by <a href="./c_m_ic_stokes.html#Stokes">Stokes' theorem</a> implies that
 </div>
 
 </div>
-<div class="core div" id="org2558f33">
+<div class="core div" id="orgf430f99">
 <p>
 \[
     {\boldsymbol \nabla} \times {\bf E} = 0.
@@ -1699,7 +1703,7 @@ falls off, has the property that the work done is independent of the path.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ef_ccd.html b/build/ems_es_ef_ccd.html
index cb193e0..173ad14 100644
--- a/build/ems_es_ef_ccd.html
+++ b/build/ems_es_ef_ccd.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,14 +1628,14 @@ calculated from Coulomb's law using the superposition principle.  Since each inf
 volume element \(d\tau' = dx' dy' dz'\) contains a charge \(dq' = \rho({\bf r}') d\tau'\), we have
 </p>
 
-<div class="eqlabel" id="org93fd4f2">
+<div class="eqlabel" id="orgc74b2f9">
 <p>
 <a id="E_vcd"></a><a href="./ems_es_ef_ccd.html#E_vcd"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org2fcc353">
+<div class="alteqlabels" id="orgaddc7cb">
 <ul class="org-ul">
 <li>Gr4 (2.8)</li>
 </ul>
@@ -1639,7 +1643,7 @@ volume element \(d\tau' = dx' dy' dz'\) contains a charge \(dq' = \rho({\bf r}')
 </div>
 
 </div>
-<div class="main div" id="orgf2f415b">
+<div class="main div" id="org81b4885">
 <p>
 
 </p>
@@ -1659,14 +1663,14 @@ Similarly, if the charge is spread out over a two-dimensional surface \({\cal S}
 \(\sigma({\bf r})\), we have over an infinitesimal area \(da'\) a charge \(dq' = \sigma({\bf r}') da'\), so
 </p>
 
-<div class="eqlabel" id="org6008079">
+<div class="eqlabel" id="orgd0ad464">
 <p>
 <a id="E_scd"></a><a href="./ems_es_ef_ccd.html#E_scd"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="orgc6962f2">
+<div class="alteqlabels" id="orgfba2df1">
 <ul class="org-ul">
 <li>Gr4(2.7)</li>
 </ul>
@@ -1674,7 +1678,7 @@ Similarly, if the charge is spread out over a two-dimensional surface \({\cal S}
 </div>
 
 </div>
-<div class="main div" id="org433e39b">
+<div class="main div" id="org743c5ef">
 <p>
 
 </p>
@@ -1691,14 +1695,14 @@ Similarly, if the charge is spread out over a two-dimensional surface \({\cal S}
 Finally, for a line path \({\cal P}\) with linear charge density \(\lambda({\bf r}')\),
 </p>
 
-<div class="eqlabel" id="orgca0563d">
+<div class="eqlabel" id="orgadea8dd">
 <p>
 <a id="E_lcd"></a><a href="./ems_es_ef_ccd.html#E_lcd"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="orgf23e73b">
+<div class="alteqlabels" id="orgcdc346f">
 <ul class="org-ul">
 <li>Gr (2.6)</li>
 </ul>
@@ -1706,7 +1710,7 @@ Finally, for a line path \({\cal P}\) with linear charge density \(\lambda({\bf
 </div>
 
 </div>
-<div class="main div" id="orgd91bb3b">
+<div class="main div" id="org2974477">
 <p>
 
 </p>
@@ -1720,7 +1724,7 @@ Finally, for a line path \({\cal P}\) with linear charge density \(\lambda({\bf
 
 </div>
 
-<div class="example div" id="orgac43438">
+<div class="example div" id="org2edb900">
 <p>
 <b>Example</b>
 </p>
@@ -1754,7 +1758,7 @@ most easily by observing that \(\frac{d}{dx} \left( \frac{x}{\sqrt{z^2 + x^2}} \
   = \frac{1}{\sqrt{z^2 + x^2}} - \frac{x^2}{(z^2 + x^2)^{3/2}} = \frac{z^2}{(z^2 + x^2)^{3/2}}\),
 leading to
 </p>
-<aside id="orgdec9553">
+<aside id="orge50da61">
 <p>
 You could alternately proceed by using changes of variables \(y = zx\) followed by \(y = \tanh \alpha\):
     \(\int_{-L}^L \frac{dx}{(z^2 + x^2)^{3/2}} = \frac{1}{z^2}
@@ -1798,7 +1802,7 @@ whereas for short distances \(z \ll L\) the field looks like that of an infinite
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ef_pc.html b/build/ems_es_ef_pc.html
index db6e583..d18fa3d 100644
--- a/build/ems_es_ef_pc.html
+++ b/build/ems_es_ef_pc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,14 +1636,14 @@ an electric field originating from the source charge.
 Invoking the superposition principle, we can thus write
 </p>
 
-<div class="eqlabel" id="org2b84014">
+<div class="eqlabel" id="orgcfc6894">
 <p>
 <a id="FqE"></a><a href="./ems_es_ef_pc.html#FqE"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org0dcd3af">
+<div class="alteqlabels" id="org89eb900">
 <ul class="org-ul">
 <li>Gr (2.3)</li>
 </ul>
@@ -1647,7 +1651,7 @@ Invoking the superposition principle, we can thus write
 </div>
 
 </div>
-<div class="core div" id="org8d0792d">
+<div class="core div" id="org4a115c3">
 <p>
 
 </p>
@@ -1663,14 +1667,14 @@ Invoking the superposition principle, we can thus write
 <p>
 with the electric field of a point charge distribution being
 </p>
-<div class="eqlabel" id="orgd7a36a0">
+<div class="eqlabel" id="orgf819bd5">
 <p>
 <a id="E_pcd"></a><a href="./ems_es_ef_pc.html#E_pcd"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a>
 </p>
-<div class="alteqlabels" id="org5d572cf">
+<div class="alteqlabels" id="org9b71fa1">
 <ul class="org-ul">
 <li>Gr (2.4)</li>
 </ul>
@@ -1678,7 +1682,7 @@ with the electric field of a point charge distribution being
 </div>
 
 </div>
-<div class="core div" id="org9d51306">
+<div class="core div" id="org31482d8">
 <p>
 
 </p>
@@ -1696,7 +1700,7 @@ The electric field \({\bf E} ({\bf r})\) is thus the force per unit charge that
 be exerted if you put a test charge at position \({\bf r}\).
 </p>
 
-<div class="example div" id="org116584f">
+<div class="example div" id="org7745fed">
 <p>
 <b>Example</b>
 </p>
@@ -1727,7 +1731,7 @@ We have \(|{\bf r} - {\bf r}'| = \sqrt{z^2 + (d/2)^2}\) for both charges and \(\
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_efo.html b/build/ems_es_efo.html
index 0b0cbee..019f8f0 100644
--- a/build/ems_es_efo.html
+++ b/build/ems_es_efo.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1638,7 +1642,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_efo_cl.html b/build/ems_es_efo_cl.html
index 654a291..9066593 100644
--- a/build/ems_es_efo_cl.html
+++ b/build/ems_es_efo_cl.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,14 +1628,14 @@ Table of contents
 <li>PM 1.4</li>
 </ul>
 
-<div class="eqlabel" id="org1390ada">
+<div class="eqlabel" id="orge02b6f1">
 <p>
 <a id="Cl"></a><a href="./ems_es_efo_cl.html#Cl"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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 </svg></a>
 </p>
-<div class="alteqlabels" id="org858a0e6">
+<div class="alteqlabels" id="org443b365">
 <ul class="org-ul">
 <li>FLS II (4.9)</li>
 <li>Gr (2.1)</li>
@@ -1643,7 +1647,7 @@ Table of contents
 </div>
 
 </div>
-<div class="core div" id="org9bc36ca">
+<div class="core div" id="org32ab786">
 <p>
 The force \(F_{t\leftarrow s}\) exerted by a point source charge \(q_s\) sitting at \({\bf r}_s\)
 on a point test charge \(q_t\) sitting at \({\bf r}_t\) is given by Coulomb's law,
@@ -1660,7 +1664,7 @@ on a point test charge \(q_t\) sitting at \({\bf r}_t\) is given by Coulomb's la
 
 </div>
 
-<aside id="org378f357">
+<aside id="orga40dbef">
 <p>
 In case you're wondering: the exact number in the denominator
 of the first equality is just \(4 \pi c^2\), so this equation really
@@ -1701,7 +1705,7 @@ in which \(\mu_0\) is the <b>vacuum permeability</b> (or alternately <i>permeabi
 with the <i>henry</i> \(H = kg~m^2 / s^2 A^2\) being the unit for inductance.
 </p>
 
-<div class="info div" id="org7f4cd99">
+<div class="info div" id="orgc9e8655">
 <p>
 <b>Info: the International System of Units</b>
 </p>
@@ -1745,7 +1749,7 @@ as \(\mu_0 = 2\alpha \frac{h}{e^2 c}\)). Its currently measured value is given i
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_efo_e.html b/build/ems_es_efo_e.html
index 8a61bad..6893ee7 100644
--- a/build/ems_es_efo_e.html
+++ b/build/ems_es_efo_e.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1661,8 +1665,14 @@ For the path, the 'angular' part is not contributing (see drawings in
 FLS II 4-3). The integral is thus purely radial,
 </p>
 
-<div class="eqlabel" id="org70d5df1">
-<div class="alteqlabels" id="org206a74a">
+<div class="eqlabel" id="org34ece66">
+<p>
+<a id="Wab"></a><a href="./ems_es_efo_e.html#Wab"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
+  <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
+  <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
+</svg></a>
+</p>
+<div class="alteqlabels" id="org003f3b8">
 <ul class="org-ul">
 <li>Gr (2.18)</li>
 </ul>
@@ -1673,7 +1683,7 @@ FLS II 4-3). The integral is thus purely radial,
 \begin{equation}
 -\int_{\bf a}^{\bf b} {\bf F} \cdot d{\bf l}
 = -\frac{q_t q_s}{4\pi \varepsilon_0} \int_{r_a}^{r_b} \frac{dr}{r^2} = \frac{q_t q_s}{4\pi \varepsilon_0} \left(\frac{1}{r_b} - \frac{1}{r_a}\right).
-\label{Gr(2.18)}
+\tag{Wab}\label{Wab}
 \end{equation}
 
 <p>
@@ -1736,7 +1746,7 @@ where in the second equality we have symmetrized the sums for convenience.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_efo_exp.html b/build/ems_es_efo_exp.html
index 2ba0d02..4896d38 100644
--- a/build/ems_es_efo_exp.html
+++ b/build/ems_es_efo_exp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1620,17 +1624,17 @@ Table of contents
 <div class="outline-text-5" id="text-ems_es_efo_exp">
 </div>
 
-<div id="outline-container-org69296e5" class="outline-6">
-<h6 id="org69296e5"><a href="#org69296e5">Before Coulomb</a></h6>
+<div id="outline-container-org5a1111b" class="outline-6">
+<h6 id="org5a1111b"><a href="#org5a1111b">Before Coulomb</a></h6>
 </div>
-<div id="outline-container-orgb1caaa1" class="outline-6">
-<h6 id="orgb1caaa1"><a href="#orgb1caaa1">Cavendish's experiment</a></h6>
+<div id="outline-container-org1c904d1" class="outline-6">
+<h6 id="org1c904d1"><a href="#org1c904d1">Cavendish's experiment</a></h6>
 </div>
-<div id="outline-container-org7ec5712" class="outline-6">
-<h6 id="org7ec5712"><a href="#org7ec5712">Coulomb</a></h6>
+<div id="outline-container-orgbc93438" class="outline-6">
+<h6 id="orgbc93438"><a href="#orgbc93438">Coulomb</a></h6>
 </div>
-<div id="outline-container-orgeddb4ba" class="outline-6">
-<h6 id="orgeddb4ba"><a href="#orgeddb4ba">Current status</a></h6>
+<div id="outline-container-org3e2f8fc" class="outline-6">
+<h6 id="org3e2f8fc"><a href="#org3e2f8fc">Current status</a></h6>
 </div>
 </div>
 
@@ -1639,7 +1643,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_efo_ps.html b/build/ems_es_efo_ps.html
index 1fc23fb..654307f 100644
--- a/build/ems_es_efo_ps.html
+++ b/build/ems_es_efo_ps.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,7 +1628,7 @@ Table of contents
 <li>PM 1.4</li>
 </ul>
 
-<div class="core div" id="org1a2d1b6">
+<div class="core div" id="org7036427">
 <p>
 Electrical forces obey the <b>principle of superposition</b>:
 the electrostatic interaction between two charged particles is left entirely
@@ -1647,7 +1651,7 @@ test charge \(q_t\) generated by a number of static point charges \(q_i\), \(i =
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep.html b/build/ems_es_ep.html
index 4f96c34..83aaa17 100644
--- a/build/ems_es_ep.html
+++ b/build/ems_es_ep.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1639,7 +1643,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_PL.html b/build/ems_es_ep_PL.html
index 9e7c09b..e42340d 100644
--- a/build/ems_es_ep_PL.html
+++ b/build/ems_es_ep_PL.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1627,7 +1631,7 @@ Our two fundamental equations for the electrostatic field are
 \]
 For the electrostatic potential, Gauss' law becomes
 </p>
-<div class="core div" id="org5d973ef">
+<div class="core div" id="org9948abe">
 <p>
 <b>The Poisson equation</b>
 \[
@@ -1640,7 +1644,7 @@ For the electrostatic potential, Gauss' law becomes
 <p>
 When the charge density vanishes, it becomes more simply
 </p>
-<div class="core div" id="org412171a">
+<div class="core div" id="org0025efb">
 <p>
 <b>The Laplace Equation</b>
 \[
@@ -1663,7 +1667,7 @@ Since the curl of a gradient is always zero, we by construction have
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_bc.html b/build/ems_es_ep_bc.html
index b14740e..2f15bae 100644
--- a/build/ems_es_ep_bc.html
+++ b/build/ems_es_ep_bc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1692,7 +1696,7 @@ if the surface charge is known.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_c.html b/build/ems_es_ep_c.html
index d9cf179..2ebfd92 100644
--- a/build/ems_es_ep_c.html
+++ b/build/ems_es_ep_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1646,7 +1650,7 @@ In the SI system where the ampere is a base unit, a volt is a \(kg m^2/s^3 A\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_d.html b/build/ems_es_ep_d.html
index 720137e..bde35fc 100644
--- a/build/ems_es_ep_d.html
+++ b/build/ems_es_ep_d.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,14 +1625,14 @@ Table of contents
 <p>
 Since this work is independent of the path chosen, we can define a function called the  <b>electrostatic potential</b>
 </p>
-<div class="eqlabel" id="org7b9d6db">
+<div class="eqlabel" id="orgf88a2fa">
 <p>
 <a id="es_pot"></a><a href="./ems_es_ep_d.html#es_pot"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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 </svg></a>
 </p>
-<div class="alteqlabels" id="org5460d6f">
+<div class="alteqlabels" id="org0c763a9">
 <ul class="org-ul">
 <li>Gr (2.21)</li>
 </ul>
@@ -1644,7 +1648,7 @@ V({\bf r}) \equiv -\int_{\cal O}^{\bf r} {\bf E} \cdot d{\bf l}
 where \({\cal O}\) is some chosen reference point. The potential difference between two points is
 well-defined without the need to specify the reference point,
 </p>
-<div class="main div" id="orgc8b6cdd">
+<div class="main div" id="org769e30b">
 <p>
 \[
     V({\bf b}) - V({\bf a}) = - \int_{\bf a}^{\bf b} {\bf E} \cdot d{\bf l}
@@ -1666,7 +1670,7 @@ V({\bf r}) = \frac{1}{4\pi \varepsilon_0} \frac{q}{r}
 The electrostatic potential moreover inherits the superposition principle from the electric field,
 so for a distribution of point charges \(q_i\) at positions \({\bf r}_i\), we have
 </p>
-<div class="core div" id="orgbee11d7">
+<div class="core div" id="org9bf457d">
 <p>
 \[
     V({\bf r}) = \frac{1}{4\pi\varepsilon_0} \sum_{i} \frac{q_i}{|{\bf r} - {\bf r}_i|}
@@ -1678,7 +1682,7 @@ so for a distribution of point charges \(q_i\) at positions \({\bf r}_i\), we ha
 <p>
 For a continuous charge density in a volume \({\cal V}\), we have
 </p>
-<div class="main div" id="org5bf43f8">
+<div class="main div" id="orgd1a1103">
 <p>
 \[
     V({\bf r}) = \frac{1}{4\pi \varepsilon_0} \int_{\cal V} d\tau' \frac{\rho({\bf r}')}{|{\bf r} - {\bf r}'|},
@@ -1690,7 +1694,7 @@ For a continuous charge density in a volume \({\cal V}\), we have
 <p>
 whereas for a surface or line charge distribution, respectively,
 </p>
-<div class="main div" id="org37f47b6">
+<div class="main div" id="org5189f33">
 <p>
 \[
     V({\bf r}) = \frac{1}{4\pi \varepsilon_0} \int_{\cal S} da' \frac{\sigma({\bf r}')}{|{\bf r} - {\bf r}'|},
@@ -1708,7 +1712,7 @@ whereas for a surface or line charge distribution, respectively,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_ex.html b/build/ems_es_ep_ex.html
index cf8c2af..4a919a6 100644
--- a/build/ems_es_ep_ex.html
+++ b/build/ems_es_ep_ex.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,7 +1622,7 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">ems.es.ep.ex</span></h5>
 <div class="outline-text-5" id="text-ems_es_ep_ex">
-<div class="example div" id="org3377487">
+<div class="example div" id="orge3478d7">
 <p>
 <b>Example 2.6</b>:  find the potential inside and outside a spherical shell or radius \(R\)
 centered at origin, which carries uniform surface charge.  Ref point at infinity.
@@ -1640,7 +1644,7 @@ V(r &lt; R) = V(R) = \frac{1}{4\pi \varepsilon_0} \frac{q}{R}.
 
 </div>
 
-<div class="example div" id="orgd302923">
+<div class="example div" id="org82d7d97">
 <p>
 <b>Example 2.7</b>:  find the potential of a uniformly charged spherical shell of radius \(R\) (same problem as 2.6, but now done with \ref{Gr(2.30)}).
 <b>Solution</b>:  Use
@@ -1683,7 +1687,7 @@ and \(V(z) = \frac{1}{4\pi \varepsilon_0} \frac{q}{R}\) inside.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_es_ep_fp.html b/build/ems_es_ep_fp.html
index e98b3b7..7a7bafb 100644
--- a/build/ems_es_ep_fp.html
+++ b/build/ems_es_ep_fp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ so
 \]
 Since this is true for any choice of \({\bf a}\) and \({\bf b}\), we have
 </p>
-<div class="core div" id="org6ea4853">
+<div class="core div" id="org1f20d4a">
 <p>
 \[
     {\bf E} = -{\boldsymbol \nabla} V
@@ -1658,7 +1662,7 @@ by using \ref{Gr(1.101)} and \ref{Gr(2.27)}.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms.html b/build/ems_ms.html
index b882940..1b16402 100644
--- a/build/ems_ms.html
+++ b/build/ems_ms.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">ems.ms</span></h3>
 
 <div class="outline-text-3" id="text-ems_ms">
-<details class="prereq" id="org9e04397">
-<summary id="org212084d">
+<details class="prereq" id="org539237f">
+<summary id="org862e5ba">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1628,8 +1632,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="orge1b5f16">
-<summary id="orgb02f584">
+<details class="objectives" id="org549de7a">
+<summary id="org2111846">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1659,7 +1663,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_BS.html b/build/ems_ms_BS.html
index c137d41..dfc45ba 100644
--- a/build/ems_ms_BS.html
+++ b/build/ems_ms_BS.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1640,7 +1644,7 @@ Then, since \(\frac{\partial \rho}{\partial t} = 0\), the continuity equation le
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_BS_sc.html b/build/ems_ms_BS_sc.html
index 4badd6d..528c5c1 100644
--- a/build/ems_ms_BS_sc.html
+++ b/build/ems_ms_BS_sc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 This is given experimentally (around 1820) by the
 </p>
-<div class="core div" id="org9388ab8">
+<div class="core div" id="org420384a">
 <p>
 {\bf Biot-Savart law}
 \[
@@ -1643,7 +1647,7 @@ with the {\it henry} \(H = kg m^2 / s^2 A^2\) being the unit for inductance.
 <p>
 For surface and volume density currents:
 </p>
-<div class="main div" id="org2d92545">
+<div class="main div" id="org09e6a02">
 <p>
 \[
     {\bf B} ({\bf r}) = \frac{\mu_0}{4\pi} \int da' \frac{{\bf K} ({\bf r}') \times ({\bf r} - {\bf r}')}{|{\bf r} - {\bf r}'|^3},
@@ -1665,7 +1669,7 @@ The {\bf superposition principle} applies here as well:  collection of currents
 the vector sum of the fields generated by the individual currents.
 </p>
 
-<div class="example div" id="org7ee0d9b">
+<div class="example div" id="org8a3ac4c">
 <p>
 \paragraph{Example 5.5:}  find \({\bf B}\) a distance \(s\) from a long straight wire carrying steady current \(I\).
 \paragraph{Solution:}  {\bf Gr Fig 5.18}:
@@ -1695,7 +1699,7 @@ f = \frac{\mu_0}{2\pi} \frac{I_1 I_2}{d}
 (like currents attract).
 </p>
 
-<div class="example div" id="orgc2a7fb9">
+<div class="example div" id="orgd6bf182">
 <p>
 \paragraph{Example 5.6:} find {\bf B} a distance \(z\) above the center of a circular loop of radius \(R\),
 carrying a steady counterclockwise current \(I\).
@@ -1715,7 +1719,7 @@ carrying a steady counterclockwise current \(I\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_dcB.html b/build/ems_ms_dcB.html
index 3973c0e..8585c30 100644
--- a/build/ems_ms_dcB.html
+++ b/build/ems_ms_dcB.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_dcB_BS.html b/build/ems_ms_dcB_BS.html
index fbdc269..275a1d5 100644
--- a/build/ems_ms_dcB_BS.html
+++ b/build/ems_ms_dcB_BS.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1646,7 +1650,7 @@ we get
 But \({\bf J}\) depends only on \({\bf r}'\) so \({\boldsymbol \nabla} \times {\bf J} ({\bf r}') = 0\), and since
 the curl of a gradient always vanishes, we obtain
 </p>
-<div class="core div" id="orgdf5fc3e">
+<div class="core div" id="org8f6dda2">
 <p>
 \[
     {\boldsymbol \nabla} \cdot {\bf B} = 0
@@ -1714,7 +1718,7 @@ at infinity), and in the third step we have used the assumption of steady-state
 <p>
 We thus obtain in total
 </p>
-<div class="core div" id="org3da2f25">
+<div class="core div" id="orga0245b5">
 <p>
 <b>Ampère's law</b>
   \[
@@ -1731,7 +1735,7 @@ We thus obtain in total
 \]
 so
 </p>
-<div class="core div" id="org5aa5f70">
+<div class="core div" id="orgdbc9d47">
 <p>
 \[
     \oint_{\cal P} {\bf B} \cdot d{\bf l} = \mu_0 I_{enc} \hspace{2cm}
@@ -1753,7 +1757,7 @@ Sign ambiguity:  resolved by right-hand rule as usual.
 Ampère's law in magnetostatics takes a parallel role to Gauss's law in electrostatics.
 </p>
 
-<div class="example div" id="orgc846872">
+<div class="example div" id="orge2cd1ba">
 <p>
 \paragraph{Example 5.7:}  same as Example 5.5, but now with Ampère.
 \paragraph{Solution:}  by symmetry, \({\bf B}\) is circumferential and can only depend on \(s\).  Then,
@@ -1765,7 +1769,7 @@ choosing an amperian loop at a fixed radius \(s\), we get
 
 </div>
 
-<div class="example div" id="org1c375de">
+<div class="example div" id="orgf268569">
 <p>
 \paragraph{Example 5.8:}  uniform surface current \({\bf K} = K \hat{\bf x}\) flowing in \(xy\) plane.
 \paragraph{Solution:}  Biot-Savart:  \({\bf B}\) must be perpendicular to \({\bf K}\).  Intuition:
@@ -1782,7 +1786,7 @@ and along \(\hat{\bf y}\) for \(z &lt; 0\).  Amperian loop of width \(l\) punchi
 
 </div>
 
-<div class="example div" id="orgc3e6b98">
+<div class="example div" id="org5e0a2eb">
 <p>
 \paragraph{Example 5.9:}  solenoid along \(\hat{\bf z}\), wire carrying current \(I\) doing \(n\) turns per unit length on cylinder of radius \(R\).
 \paragraph{Solution:}  by symmetry, \({\bf B}\) must be along axis of solenoid.  Outside:  infinitely far away, \({\bf B}\) must vanish.
@@ -1803,7 +1807,7 @@ Amperian loop of length \(l\), half-inside and half-outside:
 i) infinite straight lines, ii) infinite planes, iii) infinite solenoids, iv) toroids.
 </p>
 
-<div class="example div" id="orgb302b1e">
+<div class="example div" id="org2a86e5f">
 <p>
 \paragraph{Example 5.10:} toroidal coil (no matter the shape, as long as it is rotationally symmetric).
 \paragraph{Solution:}  magnetic field is circumferential everywhere.  Outside coil, field again zero.
@@ -1823,7 +1827,7 @@ Amperian loop half inside, half outside:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_dcB_sc.html b/build/ems_ms_dcB_sc.html
index 9c154f5..e2b0877 100644
--- a/build/ems_ms_dcB_sc.html
+++ b/build/ems_ms_dcB_sc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1648,7 +1652,7 @@ I_{enc} = \int_{\cal S} {\bf J} \cdot d{\bf a}
 \]
 Applying Stokes' theorem:
 </p>
-<div class="core div" id="org0056621">
+<div class="core div" id="orgfad8880">
 <p>
 \[
     {\boldsymbol \nabla} \times {\bf B} = \mu_0 {\bf J}
@@ -1665,7 +1669,7 @@ Applying Stokes' theorem:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_lf.html b/build/ems_ms_lf.html
index 399819b..4ceb699 100644
--- a/build/ems_ms_lf.html
+++ b/build/ems_ms_lf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_lf_c.html b/build/ems_ms_lf_c.html
index a0ae90f..5e5371b 100644
--- a/build/ems_ms_lf_c.html
+++ b/build/ems_ms_lf_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1655,7 +1659,7 @@ Since charge is conserved,
 \]
 Since this is valid for any volume, we get the
 </p>
-<div class="core div" id="org57f7f4e">
+<div class="core div" id="org0b2e371">
 <p>
 <b>continuity equation</b>
 \[
@@ -1680,7 +1684,7 @@ moving at velocity \({\bf v}\)
 \]
 </p>
 
-<div class="main div" id="org64055b4">
+<div class="main div" id="orgf2ce2c7">
 <p>
 Forces on wire, surface and volume carrying current densities:
 \[
@@ -1704,7 +1708,7 @@ Forces on wire, surface and volume carrying current densities:
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_lf_pc.html b/build/ems_ms_lf_pc.html
index 41e90d6..fce6602 100644
--- a/build/ems_ms_lf_pc.html
+++ b/build/ems_ms_lf_pc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 Force on a point charge \(q\) moving at velocity \({\bf v}\) in magnetic field \({\bf B}\):
 </p>
-<div class="core div" id="org846e982">
+<div class="core div" id="org51eb85f">
 <p>
 \[
     {\bf F}_{mag} = q {\bf v} \times {\bf B}
@@ -1633,7 +1637,7 @@ Force on a point charge \(q\) moving at velocity \({\bf v}\) in magnetic field \
 <p>
 Units of \({\bf B}\):  \(N/(A~m)\) is called a {\bf tesla} (symbol: \(T\)).  Total electromagnetic force:
 </p>
-<div class="core div" id="orgc98053f">
+<div class="core div" id="org7fd055f">
 <p>
 \[
     {\bf F}_{mag} = q ({\bf E} + {\bf v} \times {\bf B})
@@ -1643,7 +1647,7 @@ Units of \({\bf B}\):  \(N/(A~m)\) is called a {\bf tesla} (symbol: \(T\)).  Tot
 
 </div>
 
-<div class="example div" id="org638a42e">
+<div class="example div" id="orgae8d398">
 <p>
 \paragraph{Example 5.1:} cyclotron motion.  Field \({\bf B}\) pointing into page.  Charge \(q &gt; 0\) moves
 counterclockwise with speed \(v\) on a circle of radius \(R\).  Magnetic force points inwards.
@@ -1661,7 +1665,7 @@ The {\bf cyclotron frequency} is
 
 </div>
 
-<div class="example div" id="org84f5157">
+<div class="example div" id="orgac97d85">
 <p>
 \paragraph{Example 5.2:}  cycloid motion. Recommendation: {\it look at it!!}
 </p>
@@ -1684,7 +1688,7 @@ dW_{mag} = {\bf F}_{mag} \cdot d{\bf l} = q ({\bf v} \times {\bf B}) \times {\bf
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_vp.html b/build/ems_ms_vp.html
index b47b1eb..2ef4302 100644
--- a/build/ems_ms_vp.html
+++ b/build/ems_ms_vp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,7 +1626,7 @@ Table of contents
 <p>
 Since \({\boldsymbol \nabla} \cdot {\bf B} = 0\) in magnetostatics, following Helmholtz's theorem we can write
 </p>
-<div class="core div" id="org8c7f863">
+<div class="core div" id="org8d029d6">
 <p>
 \[
     {\bf B} = {\boldsymbol \nabla} \times {\bf A}
@@ -1644,7 +1648,7 @@ add any curlless function (so gradient of a scalar field) to the vector potentia
 without changing the magnetic field.  This is called a {\bf gauge choice} in electrodynamics.
 For example, we can {\bf always} eliminate the divergence of \({\bf A}\),
 </p>
-<div class="main div" id="orga7d7df6">
+<div class="main div" id="org2f5ec71">
 <p>
 {\bf Example gauge choice:}
 \[
@@ -1675,7 +1679,7 @@ zero at infinity,
 <p>
 Under this gauge choice, Ampère's law becomes
 </p>
-<div class="main div" id="org59fd103">
+<div class="main div" id="orga1e23e0">
 <p>
 \[
     {\boldsymbol \nabla}^2 {\bf A} = -\mu_0 {\bf J}
@@ -1688,7 +1692,7 @@ Under this gauge choice, Ampère's law becomes
 Note:  this is a Poisson equation for each component.
 For currents falling off sufficiently rapidly at infinity,
 </p>
-<div class="core div" id="orgb880c5e">
+<div class="core div" id="org4174f16">
 <p>
 \[
     {\bf A} ({\bf r}) = \frac{\mu_0}{4\pi} \int d\tau' \frac{J({\bf r}')}{|{\bf r} - {\bf r}'|}
@@ -1700,7 +1704,7 @@ For currents falling off sufficiently rapidly at infinity,
 <p>
 For line and surface currents, <i>(beware Griffiths' <b>horrendous</b> notation)</i>
 </p>
-<div class="main div" id="org3d2b3ad">
+<div class="main div" id="org712334e">
 <p>
 \[
     {\bf A}({\bf r}) = \frac{\mu_0}{4\pi} \int dl' \frac{{\bf I ({\bf r}')}}{|{\bf r} - {\bf r}'|},
@@ -1714,7 +1718,7 @@ For line and surface currents, <i>(beware Griffiths' <b>horrendous</b> notation)
 
 
 
-<div class="example div" id="org05a3ec0">
+<div class="example div" id="org0baf51b">
 <p>
 \paragraph{Example 5.11:}  a spherical shell of radius \(R\), carrying a uniform surface charge
 \(\sigma\), is set spinning at angular velocity \(\omega\).  Find the vector potential at \({\bf r}\).
@@ -1728,7 +1732,7 @@ the sphere is uniform !
 
 </div>
 
-<div class="example div" id="org238fce0">
+<div class="example div" id="org1f6ff4e">
 <p>
 \paragraph{Example 5.12:}  find the vector potential of an infinite solenoid with \(n\) turns
 pet unit length, radius \(R\) and current \(I\).
@@ -1788,7 +1792,7 @@ For an 'amperian' loop outside, the flux is always \(\mu_0 n I (\pi R^2)\), so
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_vp_LC.html b/build/ems_ms_vp_LC.html
index 72d64c6..0dbc611 100644
--- a/build/ems_ms_vp_LC.html
+++ b/build/ems_ms_vp_LC.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1623,7 +1627,7 @@ Table of contents
 the magnetic field of a dipole can be written in coordinate-free form.
 For this:  we define a useful object, the<br>
 </p>
-<div class="info div" id="orgb2a6e01">
+<div class="info div" id="org4607c13">
 <p>
 {\bf Levi-Civita symbol}
 \[
@@ -1693,7 +1697,7 @@ Putting back the vector notation, and the \(m\) notation for the magnetic dipole
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_vp_comp.html b/build/ems_ms_vp_comp.html
index 7aca8be..2e4ccef 100644
--- a/build/ems_ms_vp_comp.html
+++ b/build/ems_ms_vp_comp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1638,7 +1642,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_vp_mbc.html b/build/ems_ms_vp_mbc.html
index 10dce2b..5cabe04 100644
--- a/build/ems_ms_vp_mbc.html
+++ b/build/ems_ms_vp_mbc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1642,7 +1646,7 @@ B^{\parallel}_{above} - B^{\parallel}_{below} = \mu_0 K
 So:  component of \({\bf B}\) that is parallel to surface but perpendicular to current flow
 is discontinuous, whereas the one parallel to the flow is continuous.  In vector notation:
 </p>
-<div class="main div" id="org24452fb">
+<div class="main div" id="org4d0a3f0">
 <p>
 \[
     {\bf B}_{above} - {\bf B}_{below} = \mu_0 {\bf K} \times \hat{\bf n},
@@ -1654,7 +1658,7 @@ is discontinuous, whereas the one parallel to the flow is continuous.  In vector
 <p>
 where \(\hat{\bf n}\) points upwards. For the vector potential, the relations are
 </p>
-<div class="main div" id="org29a337f">
+<div class="main div" id="org945eea2">
 <p>
 \[
     {\bf A}_{above} = {\bf A}_{below}
@@ -1700,7 +1704,7 @@ What is left is
 \]
 Therefore, reidentifying the normal component, we get
 </p>
-<div class="main div" id="org0508bbe">
+<div class="main div" id="orge9e63e0">
 <p>
 \[
     \frac{\partial {\bf A}_{above}}{\partial n} - \frac{\partial {\bf A}_{below}}{\partial n}
@@ -1717,7 +1721,7 @@ Therefore, reidentifying the normal component, we get
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/ems_ms_vp_me.html b/build/ems_ms_vp_me.html
index b66ff2f..74d84ec 100644
--- a/build/ems_ms_vp_me.html
+++ b/build/ems_ms_vp_me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1673,7 +1677,7 @@ Using equation \ref{Gr(1.108)} from Problem 1.61,
 with \({\bf c} = \hat {\bf r}\),
 </p>
 
-<div class="info div" id="org5d7df6b">
+<div class="info div" id="org89234c1">
 <p>
 \paragraph{Parenthesis:  Problem 1.61 (e)}  Start from Stokes' theorem,
 \[
@@ -1715,7 +1719,7 @@ Back to our problem:
 \]
 and defining the
 </p>
-<div class="core div" id="org21dd473">
+<div class="core div" id="orgdd07882">
 <p>
 <b>magnetic dipole moment</b>
   \[
@@ -1728,7 +1732,7 @@ and defining the
 <p>
 we obtain the convenient expression for the
 </p>
-<div class="main div" id="orgf135519">
+<div class="main div" id="org72e24b4">
 <p>
 {\bf dipole term of the vector potential}
 \[
@@ -1739,7 +1743,7 @@ we obtain the convenient expression for the
 
 </div>
 
-<div class="example div" id="org2824494">
+<div class="example div" id="org74f0658">
 <p>
 \paragraph{Example 5.13:}  find magnetic dipole moment of bookend shape of Gr. Fig. 5.52.
 All sides have length \(w\) and carry current \(I\).
@@ -1773,7 +1777,7 @@ scale of the source's current loops.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm.html b/build/emsm.html
index 5c25fb3..f5c08d8 100644
--- a/build/emsm.html
+++ b/build/emsm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emsm</span></h2>
 
 <div class="outline-text-2" id="text-emsm">
-<details class="prereq" id="org868a0fe">
-<summary id="org502787e">
+<details class="prereq" id="orge4ca100">
+<summary id="orgef6f016">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1629,8 +1633,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org6ecdc3f">
-<summary id="org0baff88">
+<details class="objectives" id="org6c1e9ab">
+<summary id="orgcf2c6b6">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1656,7 +1660,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm.html b/build/emsm_esm.html
index 8c79b68..6150fdd 100644
--- a/build/emsm_esm.html
+++ b/build/emsm_esm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,7 +1629,7 @@ Table of contents
 <h4>In this section:</h4>
 <ul class="child-links-list">
 <li><a href="emsm_esm_p.html">Polarization</a><span class="headline-id">emsm.esm.p</span></li>
-<li><a href="emsm_esm_d.html">Dielectrics</a><span class="headline-id">emsm.esm.d</span></li>
+<li><a href="emsm_esm_di.html">Dielectrics</a><span class="headline-id">emsm.esm.di</span></li>
 <li><a href="emsm_esm_fpo.html">The Field of a Polarized Object</a><span class="headline-id">emsm.esm.fpo</span></li>
 <li><a href="emsm_esm_D.html">The Electric Displacement</a><span class="headline-id">emsm.esm.D</span></li>
 <li><a href="emsm_esm_di.html">Dielectrics</a><span class="headline-id">emsm.esm.di</span></li>
@@ -1633,7 +1637,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_D.html b/build/emsm_esm_D.html
index 5a403de..ef7affc 100644
--- a/build/emsm_esm_D.html
+++ b/build/emsm_esm_D.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,7 +1626,7 @@ Table of contents
 <p>
 Field due to polarization:  effectively comes from bound surface and volume charges,
 </p>
-<div class="main div" id="orgaf6a210">
+<div class="main div" id="org9531944">
 <p>
 \[
     \rho_b = -{\boldsymbol \nabla} \cdot {\bf P}, \hspace{1cm} \sigma_b = {\bf P} \cdot \hat{\bf n}.
@@ -1651,7 +1655,7 @@ Convenient way of writing:
 \]
 Defining the
 </p>
-<div class="core div" id="org0d19c33">
+<div class="core div" id="org98901f4">
 <p>
 <b>Electric displacement</b> \({\bf D}\)
   \[
@@ -1664,7 +1668,7 @@ Defining the
 <p>
 Gauss's law becomes
 </p>
-<div class="core div" id="orgba9d147">
+<div class="core div" id="org49dea26">
 <p>
 \[
     {\boldsymbol \nabla} \cdot {\bf D} = \rho_f
@@ -1676,7 +1680,7 @@ Gauss's law becomes
 <p>
 or in integral form
 </p>
-<div class="core div" id="org0c70c15">
+<div class="core div" id="orgf2cfa4b">
 <p>
 \[
     \oint d{\bf a} \cdot {\bf D} = Q_{f_{enc}}
@@ -1686,7 +1690,7 @@ or in integral form
 
 </div>
 
-<div class="example div" id="org648a1d1">
+<div class="example div" id="orgb3982f7">
 <p>
 \paragraph{Example 4.4:}  long straight wire, uniform line charge \(\lambda\), surrounded by rubber insulation
 to radius \(a\).  Find \({\bf D}\).
@@ -1734,7 +1738,7 @@ There is not 'potential' for \({\bf D}\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_D_bc.html b/build/emsm_esm_D_bc.html
index da1a182..d1c5484 100644
--- a/build/emsm_esm_D_bc.html
+++ b/build/emsm_esm_D_bc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1626,7 +1630,7 @@ D^{\perp}_{above} - D^{\perp}_{below} = \sigma_f
 \]
 Then, \ref{Gr(4.25)} give
 </p>
-<div class="main div" id="orgd235db5">
+<div class="main div" id="org245f27c">
 <p>
 \[
     {\bf D}^{\parallel}_{above} - {\bf D}^{\parallel}_{below} = {\bf P}^{\parallel}_{above} - {\bf P}^{\parallel}_{below}.
@@ -1641,7 +1645,7 @@ Then, \ref{Gr(4.25)} give
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_di.html b/build/emsm_esm_di.html
index cd65305..f09ff58 100644
--- a/build/emsm_esm_di.html
+++ b/build/emsm_esm_di.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -735,8 +739,8 @@ Table of contents
 <a href="./emsm_esm_p.html#emsm_esm_p">Polarization</a><span class="headline-id">emsm.esm.p</span>
 
 </li>
-<li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<li class="toc-currentpage">
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1612,7 +1616,7 @@ Table of contents
 </ul>
 </details>
 </nav>
-<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm_D_bc.html">Boundary Conditions&emsp;<small>[emsm.esm.D.bc]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_di_ld.html">Linear Dielectrics&emsp;<small>[emsm.esm.di.ld]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul>
+<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm_p.html">Polarization&emsp;<small>[emsm.esm.p]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_fpo.html">The Field of a Polarized Object&emsp;<small>[emsm.esm.fpo]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul>
 <h4 id="emsm_esm_di">Dielectrics<a class="headline-permalink" href="./emsm_esm_di.html#emsm_esm_di"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_di_ld.html b/build/emsm_esm_di_ld.html
index 899c458..2ad4b75 100644
--- a/build/emsm_esm_di_ld.html
+++ b/build/emsm_esm_di_ld.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1620,13 +1624,13 @@ Table of contents
 <div class="outline-text-5" id="text-emsm_esm_di_ld">
 </div>
 
-<div id="outline-container-emsm_esm_d_ld_sp" class="outline-6">
-<h6 id="emsm_esm_d_ld_sp"><a href="#emsm_esm_d_ld_sp">Susceptibility, Permittivity, Dielectric Constant</a></h6>
-<div class="outline-text-6" id="text-emsm_esm_d_ld_sp">
+<div id="outline-container-emsm_esm_di_ld_sp" class="outline-6">
+<h6 id="emsm_esm_di_ld_sp"><a href="#emsm_esm_di_ld_sp">Susceptibility, Permittivity, Dielectric Constant</a></h6>
+<div class="outline-text-6" id="text-emsm_esm_di_ld_sp">
 <p>
 For many substances:  polarization is proportional to field, if the latter isn't too strong:
 </p>
-<div class="main div" id="org5882cee">
+<div class="main div" id="org7e24b64">
 <p>
 \[
     {\bf P} = \varepsilon_0 \chi_e {\bf E}
@@ -1656,7 +1660,7 @@ In linear dielectrics:
 \]
 so
 </p>
-<div class="main div" id="orga3558f5">
+<div class="main div" id="org5a85a00">
 <p>
 \[
     {\bf D} = \varepsilon {\bf E}
@@ -1678,7 +1682,7 @@ This is all just nomenclature, everything is already in \ref{Gr(4.30)}.
 
 
 
-<div class="example div" id="org2c914e3">
+<div class="example div" id="org2569277">
 <p>
 \paragraph{Example 4.5:}  metal sphere of radius \(a\) carrying charge \(Q\), surrounded out to radius \(b\) by
 a linear dielectric material of permittivity \(\varepsilon\).  Find potential at center (relative to infinity).
@@ -1734,7 +1738,7 @@ of {\it e.g.} \({\bf P}\) would not vanish.
 Only case where parallel works:  space entirely filled with homogeneous linear dielectric.
 </p>
 
-<div class="example div" id="orgfebd47e">
+<div class="example div" id="orgabbee42">
 <p>
 \paragraph{Example 4.6:}  parallel-plate capacitor filled with insulating material of
 dielectric constant \(\varepsilon_r\).  What is the effect on the capacitance ?
@@ -1769,7 +1773,7 @@ If \(\rho = 0\), any net charge is on surface, potential then obeys Laplace.
 <p>
 Convenient to rewrite boundary conditions in terms of free charge:  from \ref{Gr(4.26)},
 </p>
-<div class="main div" id="orgb605e6c">
+<div class="main div" id="orgfd85680">
 <p>
 \[
     \varepsilon_{above} E^{\perp}_{above} - \varepsilon_{below} E^{\perp}_{below} = \sigma_f
@@ -1781,7 +1785,7 @@ Convenient to rewrite boundary conditions in terms of free charge:  from \ref{Gr
 <p>
 or in terms of the potential,
 </p>
-<div class="main div" id="orgf35ca50">
+<div class="main div" id="org3294941">
 <p>
 \[
     \varepsilon_{above} \frac{\partial V_{above}}{\partial n} -
@@ -1794,7 +1798,7 @@ or in terms of the potential,
 <p>
 Potential itself is continuous,
 </p>
-<div class="main div" id="org5c553e0">
+<div class="main div" id="org1881d42">
 <p>
 \[
     V_{above} = V_{below}
@@ -1806,7 +1810,7 @@ Potential itself is continuous,
 
 
 
-<div class="example div" id="orgf527756">
+<div class="example div" id="org197c783">
 <p>
 \paragraph{Example 4.7:}  sphere of homogeneous dielectric material in uniform electric field \({\bf E}_0\).
 Find electric field inside sphere.
@@ -1864,7 +1868,7 @@ Thus,
 
 
 
-<div class="example div" id="orgaa2beb6">
+<div class="example div" id="org312cdc8">
 <p>
 \paragraph{Example 4.8:}  suppose region below \(z = 0\) is filled with uniform linear dielectric with susceptibility \(\chi_e\).
 Calculate force on point charge \(q\) situated a distance \(d\) above origin.
@@ -1968,7 +1972,7 @@ Special case of linear isotropic dielectric:  \({\bf D} = \varepsilon {\bf E}\),
 \]
 Total work done:
 </p>
-<div class="main div" id="org9a3cd32">
+<div class="main div" id="org1d22441">
 <p>
 \[
     W = \frac{1}{2} \int d\tau {\bf D} \cdot {\bf E}
@@ -2059,7 +2063,7 @@ so like before but with the correct sign.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_fpo.html b/build/emsm_esm_fpo.html
index f129140..1e39949 100644
--- a/build/emsm_esm_fpo.html
+++ b/build/emsm_esm_fpo.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1612,7 +1616,7 @@ Table of contents
 </ul>
 </details>
 </nav>
-<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm_d.html">Dielectrics&emsp;<small>[emsm.esm.d]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_fpo_pibc.html">Physical Interpretation of Bound Charges&emsp;<small>[emsm.esm.fpo.pibc]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul>
+<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm_di.html">Dielectrics&emsp;<small>[emsm.esm.di]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_fpo_pibc.html">Physical Interpretation of Bound Charges&emsp;<small>[emsm.esm.fpo.pibc]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul>
 <h4 id="emsm_esm_fpo">The Field of a Polarized Object<a class="headline-permalink" href="./emsm_esm_fpo.html#emsm_esm_fpo"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
@@ -1662,7 +1666,7 @@ V({\bf r}) = \frac{1}{4\pi\varepsilon_0} \oint_{\cal S} d{\bf a}' ⋅ \frac{{\bf
 \]
 Interpretation:  first terms is like contribution of a surface charge,
 </p>
-<div class="main div" id="org5c31a10">
+<div class="main div" id="org0db0ed1">
 <p>
 \[
     \sigma_b({\bf r}) = {\bf P} ({\bf r}) \cdot \hat{\bf n}
@@ -1674,7 +1678,7 @@ Interpretation:  first terms is like contribution of a surface charge,
 <p>
 and second term looks like contribution of a volume charge,
 </p>
-<div class="main div" id="org2c0c9b0">
+<div class="main div" id="orgf6835b7">
 <p>
 \[
     \rho_b ({\bf r}) = -{\boldsymbol \nabla} \cdot {\bf P} ({\bf r})
@@ -1686,7 +1690,7 @@ and second term looks like contribution of a volume charge,
 <p>
 Using these definitions,
 </p>
-<div class="main div" id="orgec07570">
+<div class="main div" id="orgaff40e6">
 <p>
 \[
   V({\bf r}) = \frac{1}{4\pi\varepsilon_0} \oint_{\cal S} d{\bf a}' ⋅ \frac{σ_b ({\bf r}')}{|{\bf r} - {\bf r}'|}
@@ -1705,7 +1709,7 @@ These {\bf bound charges} faithfully represent the object's sources for electric
 </p>
 
 
-<div class="example div" id="org3291100">
+<div class="example div" id="orgd5d2cc0">
 <p>
 \paragraph{Example 4.2:}  electric field produced by uniformly polarized sphere of radius \(R\).
 \paragraph{Solution:}  put \(z\) axis along \({\bf P}\).  Since \({\bf P}\) is uniform, \(\rho_b = 0\).
@@ -1751,7 +1755,7 @@ where the total dipole moment is simply the integral over the polarization,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_fpo_fid.html b/build/emsm_esm_fpo_fid.html
index c73fe97..6a2a9db 100644
--- a/build/emsm_esm_fpo_fid.html
+++ b/build/emsm_esm_fpo_fid.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1650,7 +1654,7 @@ this is given by \ref{Gr(3.105)} (see Example below)
 irrespective of charge distribution within sphere.
 </p>
 
-<div class="example div" id="org38db1b4">
+<div class="example div" id="orge9b3f2f">
 <p>
 \paragraph{Problem 3.47:}  show that the average field inside sphere of radius \(R\) due to all charges within
 the sphere is
@@ -1745,7 +1749,7 @@ where \({\cal V}\) is the entire volume of the dielectric.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_fpo_pibc.html b/build/emsm_esm_fpo_pibc.html
index ce202e1..8a4aa06 100644
--- a/build/emsm_esm_fpo_pibc.html
+++ b/build/emsm_esm_fpo_pibc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1648,7 +1652,7 @@ Volume charge:  drawing of diverging polarization.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_p.html b/build/emsm_esm_p.html
index 84aafaa..e0f37ae 100644
--- a/build/emsm_esm_p.html
+++ b/build/emsm_esm_p.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1612,7 +1616,7 @@ Table of contents
 </ul>
 </details>
 </nav>
-<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_d.html">Dielectrics&emsp;<small>[emsm.esm.d]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul><div id="outline-container-emsm_esm_p" class="outline-4">
+<ul class="navigation-links"><li>Prev:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li><li>Next:&nbsp;<a href="emsm_esm_di.html">Dielectrics&emsp;<small>[emsm.esm.di]</small></a></li><li>Up:&nbsp;<a href="emsm_esm.html">Electrostatics in matter&emsp;<small>[emsm.esm]</small></a></li></ul><div id="outline-container-emsm_esm_p" class="outline-4">
 <h4 id="emsm_esm_p">Polarization<a class="headline-permalink" href="./emsm_esm_p.html#emsm_esm_p"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
@@ -1700,7 +1704,7 @@ dipole moment pointing from \(O^-\) along bisector.
 <p>
 Torque on dipole:  if field is uniform, overall force on dipole cancels, but torque remains:
 </p>
-<div class="main div" id="org8c49d29">
+<div class="main div" id="orgef1b61c">
 <p>
 {\bf Torque on a dipole:}
 \[
@@ -1717,7 +1721,7 @@ If field is non-uniform,
    \]
 so
 </p>
-<div class="main div" id="orgebe5d30">
+<div class="main div" id="org4237fed">
 <p>
 \[
    {\bf F} = ({\bf p} \cdot {\boldsymbol \nabla}) {\bf E}
@@ -1761,7 +1765,7 @@ or rather {\bf ferroelectricity} (after {\bf ferromagnetism}, which is the corre
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_esm_s.html b/build/emsm_esm_s.html
index 7de5435..d48ac3f 100644
--- a/build/emsm_esm_s.html
+++ b/build/emsm_esm_s.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1625,7 +1629,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm.html b/build/emsm_msm.html
index 474de6b..c31177b 100644
--- a/build/emsm_msm.html
+++ b/build/emsm_msm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">emsm.msm</span></h3>
 
 <div class="outline-text-3" id="text-emsm_msm">
-<details class="prereq" id="orgc41bdc3">
-<summary id="org728410e">
+<details class="prereq" id="org012b8fb">
+<summary id="org2ce111c">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1629,8 +1633,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="org92b6a43">
-<summary id="orgcba9d30">
+<details class="objectives" id="org015b5e7">
+<summary id="org6c1f1e4">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1656,7 +1660,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_H.html b/build/emsm_msm_H.html
index 1c07bda..1eea28c 100644
--- a/build/emsm_msm_H.html
+++ b/build/emsm_msm_H.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_H_A.html b/build/emsm_msm_H_A.html
index f85bb12..0fbb6a9 100644
--- a/build/emsm_msm_H_A.html
+++ b/build/emsm_msm_H_A.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Ampère's law:
 \]
 so we can define
 </p>
-<div class="core div" id="org7198265">
+<div class="core div" id="orgbb82e02">
 <p>
 \[
     {\bf H} \equiv \frac{1}{\mu_0} {\bf B} - {\bf M}
@@ -1644,7 +1648,7 @@ so we can define
 <p>
 and rewrite Ampère's law as
 </p>
-<div class="core div" id="orgbb9b573">
+<div class="core div" id="org6e28dfc">
 <p>
 \[
     {\boldsymbol \nabla} \times {\bf H} = {\bf J}_f
@@ -1656,7 +1660,7 @@ and rewrite Ampère's law as
 <p>
 or in integral form,
 </p>
-<div class="core div" id="org09c80be">
+<div class="core div" id="orgfc4cbdf">
 <p>
 \[
     \oint {\bf H} \cdot d{\bf l} = I_{f_{enc}}
@@ -1670,7 +1674,7 @@ or in integral form,
 rewrite Ampère's law in terms of free currents alone.  Bound currents come along for the ride.
 </p>
 
-<div class="example div" id="orgc19ac8e">
+<div class="example div" id="orged9fb55">
 <p>
 \paragraph{Example 6.2:}  long copper rod radius \({\bf R}\) carries uniformly distributed free current \(I\).
 Find \({\bf H}\) inside and outside rod.
@@ -1776,7 +1780,7 @@ and
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_a.html b/build/emsm_msm_a.html
index 9366379..e0feb8c 100644
--- a/build/emsm_msm_a.html
+++ b/build/emsm_msm_a.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1667,7 +1671,7 @@ Fun fact: a paramagnet attracted into the field, whereas a diamagnet is repelled
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_fmo.html b/build/emsm_msm_fmo.html
index f8dcb4e..9f665c3 100644
--- a/build/emsm_msm_fmo.html
+++ b/build/emsm_msm_fmo.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_fmo_bc.html b/build/emsm_msm_fmo_bc.html
index 51205be..17f2f01 100644
--- a/build/emsm_msm_fmo_bc.html
+++ b/build/emsm_msm_fmo_bc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ For a single dipole:  refer to \ref{Gr(5.83)} (vector potential of single dipole
 For a chunk of material with local magnetization \({\bf M} ({\bf r})\),
 by the principle of superposition we thus have:
 </p>
-<div class="main div" id="orgcc63d5d">
+<div class="main div" id="orge334af5">
 <p>
 \[
     {\bf A} ({\bf r}) = \frac{\mu_0}{4\pi} \int_{\cal V} d\tau' ~\frac{{\bf M} ({\bf r}') \times ({\bf r} - {\bf r}')}{|{\bf r} - {\bf r}'|^3}
@@ -1671,7 +1675,7 @@ Problem 1.61 b) (p.56):  leads to
 \]
 Reinterpretation:  first term: potential from volume current,
 </p>
-<div class="main div" id="org2a43517">
+<div class="main div" id="org6918802">
 <p>
 \[
     {\bf J}_b = {\boldsymbol \nabla} \times {\bf M}
@@ -1683,7 +1687,7 @@ Reinterpretation:  first term: potential from volume current,
 <p>
 second term:  potential from surface current,
 </p>
-<div class="main div" id="org78e636c">
+<div class="main div" id="org4df5f2f">
 <p>
 \[
     {\bf K}_b = {\bf M} \times \hat{\bf n}
@@ -1695,7 +1699,7 @@ second term:  potential from surface current,
 <p>
 With these definitions,
 </p>
-<div class="main div" id="org258eef0">
+<div class="main div" id="orge6fb0a7">
 <p>
 \[
   {\bf A} ({\bf r}) = \frac{\mu_0}{4\pi} ∫_{\cal V} dτ' \frac{{\bf J}_b ({\bf r}')}{|{\bf r} - {\bf r}'|}
@@ -1716,7 +1720,7 @@ in the volume and surface of the material.
 
 
 
-<div class="example div" id="org167263a">
+<div class="example div" id="org61adab0">
 <p>
 \paragraph{Example 6.1:}  find field of uniformly magnetized sphere.
 \paragraph{Solution:}  put z axis along \({\bf M}\).
@@ -1749,7 +1753,7 @@ inside sphere, whereas outside:  pure dipole field, with
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_fmo_fim.html b/build/emsm_msm_fmo_fim.html
index 0b9fd0f..b8df5bd 100644
--- a/build/emsm_msm_fmo_fim.html
+++ b/build/emsm_msm_fmo_fim.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1627,7 +1631,7 @@ As per electric case.  Reasoning done in Problem 6.11.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_fmo_pibc.html b/build/emsm_msm_fmo_pibc.html
index 0a8b620..0c0dc41 100644
--- a/build/emsm_msm_fmo_pibc.html
+++ b/build/emsm_msm_fmo_pibc.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ unless non-uniform, or at the edge.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_lnlm.html b/build/emsm_msm_lnlm.html
index ba37ad2..b28b304 100644
--- a/build/emsm_msm_lnlm.html
+++ b/build/emsm_msm_lnlm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_lnlm_fm.html b/build/emsm_msm_lnlm_fm.html
index 40e2fca..9d81bfa 100644
--- a/build/emsm_msm_lnlm_fm.html
+++ b/build/emsm_msm_lnlm_fm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,7 +1632,7 @@ to paramagnetic at about \(770^\circ C\).  {\bf Phase transitions}.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_lnlm_sp.html b/build/emsm_msm_lnlm_sp.html
index 910337f..5c9af8b 100644
--- a/build/emsm_msm_lnlm_sp.html
+++ b/build/emsm_msm_lnlm_sp.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1623,7 +1627,7 @@ In para/diamagnets:  when \({\bf B}\) is removed, \({\bf M}\) disappears.  For n
 fields, proportionality.  Custom (slightly different than for dielectrics):
 {\bf magnetic susceptibility} \(\chi_m\) defined as
 </p>
-<div class="core div" id="org82feea4">
+<div class="core div" id="org29b4c9e">
 <p>
 \[
     {\bf M} = \chi_m {\bf H}
@@ -1668,7 +1672,7 @@ In linear medium:  bound volume current proportional to free current,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_m.html b/build/emsm_msm_m.html
index d8f5e66..139274a 100644
--- a/build/emsm_msm_m.html
+++ b/build/emsm_msm_m.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_m_dpf.html b/build/emsm_msm_m_dpf.html
index 87f3c2d..ff26c6a 100644
--- a/build/emsm_msm_m_dpf.html
+++ b/build/emsm_msm_m_dpf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,8 +1633,8 @@ Table of contents
 </p>
 </div>
 
-<div id="outline-container-org5ab66c1" class="outline-6">
-<h6 id="org5ab66c1"><a href="#org5ab66c1">Why is Ferromagnetism such an intriguing phenomenon?</a></h6>
+<div id="outline-container-org987dae1" class="outline-6">
+<h6 id="org987dae1"><a href="#org987dae1">Why is Ferromagnetism such an intriguing phenomenon?</a></h6>
 </div>
 </div>
 
@@ -1641,7 +1645,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/emsm_msm_m_fdi.html b/build/emsm_msm_m_fdi.html
index 03dc47e..b595767 100644
--- a/build/emsm_msm_m_fdi.html
+++ b/build/emsm_msm_m_fdi.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 Torque on magnetic dipole:
 </p>
-<div class="core div" id="org0cca13e">
+<div class="core div" id="orgc6e3ebf">
 <p>
 \[
     {\bf N} = {\bf m} \times {\bf B}
@@ -1639,7 +1643,7 @@ Similar to electric analogue, \ref{Gr(4.4)}, \({\bf N} = {\bf p} \times {\bf E}\
 <p>
 In a non-uniform field: (to be done in Problem 6.4):
 </p>
-<div class="main div" id="org170e96e">
+<div class="main div" id="org7d31f3d">
 <p>
 \[
     {\bf F} = {\boldsymbol \nabla} ({\bf m} \cdot {\bf B})
@@ -1655,7 +1659,7 @@ In a non-uniform field: (to be done in Problem 6.4):
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/in.html b/build/in.html
index 6fb703c..66be397 100644
--- a/build/in.html
+++ b/build/in.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1630,7 +1634,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/in_p.html b/build/in_p.html
index 95919b9..4d32d4a 100644
--- a/build/in_p.html
+++ b/build/in_p.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1622,6 +1626,29 @@ Table of contents
 These lecture notes provide a full treatment of classical (<i>pre-quantum</i>)
 electromagnetic phenomena (static and dynamic).
 </p>
+
+<p>
+<b>Health warning</b>: this is all very much still under construction.
+</p>
+
+<p>
+<b>Authoring format</b>: I am developing an new authoring toolset based on
+<a href="https://orgmode.org/">Org</a> files with custom export scripts, having
+as end product an <a href="https://html.spec.whatwg.org/multipage/">HTML</a>
+multipage, interlinked static site. You can view the site
+<a href="https://jscaux.org/ln/pqed">here</a> (always giving the most up-to-date
+version) or pull it to your local machine
+by using the <a href="https://jscaux.org/git/jscaux/pqed_html">static html repo</a>
+(mostly up-to-date; make sure you pull on a regular basis).
+</p>
+
+
+<p>
+Your feedback (and also tolerance and patience) is most welcome.
+You can either <a href="mailto:prof@jscaux.org">email me</a> directly or
+<a href="https://jscaux.org/git/jscaux/pqed_html/issues">create an issue</a> in
+the static html repo.
+</p>
 </div>
 </div>
 
@@ -1630,7 +1657,7 @@ electromagnetic phenomena (static and dynamic).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/in_t.html b/build/in_t.html
index a71ce32..d56498c 100644
--- a/build/in_t.html
+++ b/build/in_t.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1612,7 +1616,7 @@ Table of contents
 </ul>
 </details>
 </nav>
-<ul class="navigation-links"><li>Prev:&nbsp;<a href="in_p.html">Preface&emsp;<small>[in.p]</small></a></li><li>Next:&nbsp;<a href="in_t_c.html">Contextual colors&emsp;<small>[in.t.c]</small></a></li><li>Up:&nbsp;<a href="in.html">Introduction&emsp;<small>[in]</small></a></li></ul>
+<ul class="navigation-links"><li>Prev:&nbsp;<a href="in_p.html">Preface&emsp;<small>[in.p]</small></a></li><li>Next:&nbsp;<a href="in_t_l.html">Section and equation labelling&emsp;<small>[in.t.l]</small></a></li><li>Up:&nbsp;<a href="in.html">Introduction&emsp;<small>[in]</small></a></li></ul>
 <h3 id="in_t">Tips for the reader<a class="headline-permalink" href="./in_t.html#in_t"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
@@ -1624,12 +1628,13 @@ Table of contents
 
 <h4>In this section:</h4>
 <ul class="child-links-list">
+<li><a href="in_t_l.html">Section and equation labelling</a><span class="headline-id">in.t.l</span></li>
 <li><a href="in_t_c.html">Contextual colors</a><span class="headline-id">in.t.c</span></li>
 </ul>
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/in_t_c.html b/build/in_t_c.html
index 6bd81c6..1789af1 100644
--- a/build/in_t_c.html
+++ b/build/in_t_c.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -271,6 +271,10 @@ Table of contents
 
 </summary>
 <ul>
+<li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
 <li class="toc-currentpage">
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1612,7 +1616,7 @@ Table of contents
 </ul>
 </details>
 </nav>
-<ul class="navigation-links"><li>Prev:&nbsp;<a href="in_t.html">Tips for the reader&emsp;<small>[in.t]</small></a></li><li>Next:&nbsp;<a href="ems.html">Electromagnetostatics&emsp;<small>[ems]</small></a></li><li>Up:&nbsp;<a href="in_t.html">Tips for the reader&emsp;<small>[in.t]</small></a></li></ul><div id="outline-container-in_t_c" class="outline-4">
+<ul class="navigation-links"><li>Prev:&nbsp;<a href="in_t_l.html">Section and equation labelling&emsp;<small>[in.t.l]</small></a></li><li>Next:&nbsp;<a href="ems.html">Electromagnetostatics&emsp;<small>[ems]</small></a></li><li>Up:&nbsp;<a href="in_t.html">Tips for the reader&emsp;<small>[in.t]</small></a></li></ul><div id="outline-container-in_t_c" class="outline-4">
 <h4 id="in_t_c">Contextual colors<a class="headline-permalink" href="./in_t_c.html#in_t_c"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
   <path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
@@ -1623,8 +1627,8 @@ Throughout these lecture notes, boxes with contextual colors are used,
 serving specific purposes. These are:
 </p>
 
-<details class="prereq" id="org91066c2">
-<summary id="orga77b565">
+<details class="prereq" id="orgd19ffcb">
+<summary id="org7e6b42e">
 Prerequisites
 </summary>
 <p>
@@ -1637,8 +1641,8 @@ Specific prerequisites for understanding the upcoming material
 </ul>
 </details>
 
-<details class="objectives" id="org1a04dff">
-<summary id="org62a2ee2">
+<details class="objectives" id="org8804e8c">
+<summary id="orgbd0e57b">
 Objectives
 </summary>
 <p>
@@ -1651,8 +1655,8 @@ Objectives for this part: what you should learn by reading this
 </ul>
 </details>
 
-<details class="core" id="orga6f2434">
-<summary id="org1d41d26">
+<details class="core" id="org6280229">
+<summary id="org97651f6">
 Core
 </summary>
 <p>
@@ -1660,8 +1664,8 @@ Core material: you have to know this by heart, and how to use it.
 </p>
 </details>
 
-<details class="main" id="org752e1e7">
-<summary id="orgc020804">
+<details class="main" id="orgee1d988">
+<summary id="org2093082">
 Main
 </summary>
 <p>
@@ -1669,8 +1673,8 @@ Main matter which you should know how to use.
 </p>
 </details>
 
-<details class="example" id="orgdd3c2cf">
-<summary id="org6d5a02a">
+<details class="example" id="org225b854">
+<summary id="org090929f">
 Example
 </summary>
 <p>
@@ -1678,8 +1682,8 @@ Example of the concepts just covered.
 </p>
 </details>
 
-<details class="info" id="org2d5f663">
-<summary id="orgc19da7d">
+<details class="info" id="org9cb97d4">
+<summary id="orga17a3bf">
 Info
 </summary>
 <p>
@@ -1687,8 +1691,8 @@ Additional (contextual) information.
 </p>
 </details>
 
-<details class="context" id="org0da3936">
-<summary id="org211a5c8">
+<details class="context" id="orgaad9c47">
+<summary id="org0d001e8">
 Historical Context
 </summary>
 <p>
@@ -1701,7 +1705,7 @@ Additional historical context.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/index.html b/build/index.html
index 7d0cc0e..5032460 100644
--- a/build/index.html
+++ b/build/index.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1628,6 +1632,7 @@ Table of contents
 <li>
 <a href="./in_t.html#in_t">Tips for the reader</a><span class="headline-id">in.t</span>
 <ul>
+<li><a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span></li>
 <li><a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span></li>
 </ul>
 </li>
@@ -1779,7 +1784,7 @@ Table of contents
 <a href="./emsm_esm.html#emsm_esm">Electrostatics in matter</a><span class="headline-id">emsm.esm</span>
 <ul>
 <li><a href="./emsm_esm_p.html#emsm_esm_p">Polarization</a><span class="headline-id">emsm.esm.p</span></li>
-<li><a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span></li>
+<li><a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span></li>
 <li>
 <a href="./emsm_esm_fpo.html#emsm_esm_fpo">The Field of a Polarized Object</a><span class="headline-id">emsm.esm.fpo</span>
 <ul>
@@ -2086,7 +2091,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/qed.html b/build/qed.html
index b4d7335..576d304 100644
--- a/build/qed.html
+++ b/build/qed.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1629,7 +1633,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/qed_t.html b/build/qed_t.html
index 351d2a3..acdd4ab 100644
--- a/build/qed_t.html
+++ b/build/qed_t.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1624,7 +1628,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red.html b/build/red.html
index 27624a5..3db0e95 100644
--- a/build/red.html
+++ b/build/red.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1619,8 +1623,8 @@ Table of contents
 </svg></a><span class="headline-id">red</span></h2>
 
 <div class="outline-text-2" id="text-red">
-<details class="prereq" id="orgddfdc6f">
-<summary id="orgeca22d4">
+<details class="prereq" id="orgb9fcc7f">
+<summary id="org8a591da">
 Prerequisites
 </summary>
 <ul class="org-ul">
@@ -1628,8 +1632,8 @@ Prerequisites
 </ul>
 </details>
 
-<details class="objectives" id="orgc04530a">
-<summary id="org3393f09">
+<details class="objectives" id="orgd8102cf">
+<summary id="org92aa1b0">
 Objectives
 </summary>
 <ul class="org-ul">
@@ -1659,7 +1663,7 @@ Objectives
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rem.html b/build/red_rem.html
index 637b27b..f874ae6 100644
--- a/build/red_rem.html
+++ b/build/red_rem.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1632,7 +1636,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rem_Fmunu.html b/build/red_rem_Fmunu.html
index 3420a44..a8f345e 100644
--- a/build/red_rem_Fmunu.html
+++ b/build/red_rem_Fmunu.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1688,7 +1692,7 @@ how the nonvanishing elements of an antisymmetric tensor transform:
 <p>
 Comparing with the transformation rules for the electromagnetic field which we obtained in (\ref{eq:EMFieldsLorentzTransfo}), we can define the
 </p>
-<div class="core div" id="orga725a53">
+<div class="core div" id="org59626ea">
 <p>
 {\bf Electromagnetic Field Tensor}
 \[
@@ -1704,7 +1708,7 @@ Comparing with the transformation rules for the electromagnetic field which we o
 <p>
 together with the handy
 </p>
-<div class="main div" id="org14dbfc2">
+<div class="main div" id="org54e2473">
 <p>
 {\bf Dual Field Tensor}
 \[
@@ -1728,7 +1732,7 @@ obtained from the field tensor by the substitution
 <p>
 Our electromagnetic field transformation laws then become the simple
 </p>
-<div class="core div" id="org8c48487">
+<div class="core div" id="org1eec6b9">
 <p>
 {\bf Lorentz Transformation Rules for EM Fields}
 \[
@@ -1745,7 +1749,7 @@ Our electromagnetic field transformation laws then become the simple
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rem_Ltf.html b/build/red_rem_Ltf.html
index 382b8cc..bc2917f 100644
--- a/build/red_rem_Ltf.html
+++ b/build/red_rem_Ltf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1741,7 +1745,7 @@ These factors cancel so \(\bar{B}_x = B_x\).
 <p>
 We thus obtain the
 </p>
-<div class="core div" id="org5b061dd">
+<div class="core div" id="org226702b">
 <p>
 {\bf EM field transformation laws (motion along \(x\) with velocity \(v\))}
 </p>
@@ -1785,7 +1789,7 @@ so
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rem_Me.html b/build/red_rem_Me.html
index 9d030e8..c077b7e 100644
--- a/build/red_rem_Me.html
+++ b/build/red_rem_Me.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1642,7 +1646,7 @@ We thus obtain
 \]
 Recognizing the proper velocity, we thus get that charge density and current density can together form the
 </p>
-<div class="core div" id="org07127c5">
+<div class="core div" id="org880d382">
 <p>
 {\bf Current density 4-vector}
 \[
@@ -1655,7 +1659,7 @@ Recognizing the proper velocity, we thus get that charge density and current den
 <p>
 The continuity equation (\ref{eq:continuity}) takes the simple form
 </p>
-<div class="core div" id="org29413f7">
+<div class="core div" id="orge750de3">
 <p>
 {\bf Continuity equation}
 \[
@@ -1667,7 +1671,7 @@ The continuity equation (\ref{eq:continuity}) takes the simple form
 <p>
 while similarly the notation simplifies for
 </p>
-<div class="main div" id="org23e96f4">
+<div class="main div" id="org08f0a21">
 <p>
 {\bf Maxwell's equations}
 \[
@@ -1682,7 +1686,7 @@ while similarly the notation simplifies for
 <p>
 In terms of \(F^{\mu \nu}\) and the proper velocity \(\eta^\mu\), we also have the
 </p>
-<div class="main div" id="orgd035fe4">
+<div class="main div" id="orgffda03f">
 <p>
 {\bf Minkowski force on a charge \(q\)}
 \[
@@ -1732,7 +1736,7 @@ the Lorenz gauge (\ref{eq:InhomogeneousMaxwellLorenzGauge}) here expressed as
 \]
 Defining the
 </p>
-<div class="main div" id="orgc5f279e">
+<div class="main div" id="org60385bf">
 <p>
 {\bf d'Alembertian operator}
 \[
@@ -1745,7 +1749,7 @@ Defining the
 we obtain the final form of
 </p>
 
-<div class="core div" id="orgfbac8d0">
+<div class="core div" id="org1ba8f7d">
 <p>
 {\bf Maxwell's equations (Lorenz gauge, 4-vector notation)}
 \[
@@ -1764,7 +1768,7 @@ of these equations.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rem_mre.html b/build/red_rem_mre.html
index 4f95d22..41ed77d 100644
--- a/build/red_rem_mre.html
+++ b/build/red_rem_mre.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1627,7 +1631,7 @@ implies the existence of magnetism, and vice-versa.
 <p>
 To illustrate this, we take a simple example
 </p>
-<aside id="orgfedf3e0">
+<aside id="orgb1e965e">
 <p>
 See Purcell \&amp; Morin, section 5.9.
 </p>
@@ -1714,7 +1718,7 @@ magnetic field of a long straight wire carrying current \(I\).
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rm.html b/build/red_rm.html
index ee457c7..7f62d9b 100644
--- a/build/red_rm.html
+++ b/build/red_rm.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rm_Mf.html b/build/red_rm_Mf.html
index 440b65a..e0d0f09 100644
--- a/build/red_rm_Mf.html
+++ b/build/red_rm_Mf.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1621,7 +1625,7 @@ Table of contents
 <p>
 Newton's second law remains valid provided we use the relativistic momentum:
 </p>
-<div class="core div" id="org5f5dca8">
+<div class="core div" id="orgfa4da27">
 <p>
 {\bf Newton's law (relativistic case)}
 \[
@@ -1631,7 +1635,7 @@ Newton's second law remains valid provided we use the relativistic momentum:
 
 </div>
 
-<div class="example div" id="org00f4851">
+<div class="example div" id="orgb0542e8">
 <p>
 \paragraph{Example 12.10: Motion under a constant force.} A particle
 of mass \(m\) is subjected to a constant force \(F\). If it starts at the
@@ -1722,7 +1726,7 @@ The way to avoid complicated transformation rules is to define a four-vector
 as the derivative of momentum with respect to proper time, which leads to
 the definition of the
 </p>
-<div class="main div" id="org96b7d74">
+<div class="main div" id="orgfce9eb8">
 <p>
 {\bf Minkowski force}
 \[
@@ -1746,7 +1750,7 @@ whose zeroth component is defined as \(1/c\) times the rate of increase of energ
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rm_pt.html b/build/red_rm_pt.html
index 0d436eb..d43dbcd 100644
--- a/build/red_rm_pt.html
+++ b/build/red_rm_pt.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1634,7 +1638,7 @@ and this is called the {\bf ordinary velocity}.
 The {\bf proper velocity} is defined as the hybrid-frame quantity
 (distance as measured on the ground) divided by (proper time interval):
 </p>
-<div class="core div" id="orgfd09da9">
+<div class="core div" id="orgf476526">
 <p>
 {\bf Proper velocity}
 \[
@@ -1656,7 +1660,7 @@ By adding the zeroth component
 \]
 we can define the
 </p>
-<div class="core div" id="org0da6816">
+<div class="core div" id="org3faa2b1">
 <p>
 {\bf four-velocity} or {\bf proper velocity four-vector}
 \[
@@ -1691,7 +1695,7 @@ for our usual relative frame velocity of \(v\) in the \(x\) direction,
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_rm_rme.html b/build/red_rm_rme.html
index 2b83e7f..5a600b1 100644
--- a/build/red_rm_rme.html
+++ b/build/red_rm_rme.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1618,7 +1622,7 @@ Table of contents
   <path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
 </svg></a><span class="headline-id">red.rm.rme</span></h4>
 <div class="outline-text-4" id="text-red_rm_rme">
-<div class="core div" id="org7e93baa">
+<div class="core div" id="orgb552421">
 <p>
 The {\bf relativistic momentum} \({\boldsymbol p}\) is defined as
 \[
@@ -1640,7 +1644,7 @@ These can be combined into the {\bf energy-momentum four-vector}
 <p>
 When the object is stationary, its energy is the
 </p>
-<div class="core div" id="org3549d8a">
+<div class="core div" id="org67c38cb">
 <p>
 {\bf Rest energy}
 \[
@@ -1653,7 +1657,7 @@ When the object is stationary, its energy is the
 When moving, the difference between relativistic and rest energies
 is the
 </p>
-<div class="core div" id="org2d5bf1f">
+<div class="core div" id="org251ada4">
 <p>
 {\bf Kinetic energy}
 \[
@@ -1673,7 +1677,7 @@ this to
 <p>
 In a closed system,
 </p>
-<div class="core div" id="orgf13bbad">
+<div class="core div" id="orgc2b8494">
 <p>
 {\bf Total relativistic energy and momentum is conserved}
 \[
@@ -1694,7 +1698,7 @@ N.B.: don't confuse an {\bf invariant} quantity with a {\bf conserved} quantity.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_sr.html b/build/red_sr.html
index e3b278c..3cb0d6c 100644
--- a/build/red_sr.html
+++ b/build/red_sr.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1631,7 +1635,7 @@ Table of contents
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_sr_4v.html b/build/red_sr_4v.html
index 0c27410..59884b3 100644
--- a/build/red_sr_4v.html
+++ b/build/red_sr_4v.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1626,7 +1630,7 @@ Table of contents
 \]
 The Lorentz transformation then reads
 </p>
-<div class="core div" id="org0d12d70">
+<div class="core div" id="org1a15489">
 <p>
 {\bf Lorentz transformation (motion along \(x\) at velocity \(v\))}
 \[
@@ -1662,7 +1666,7 @@ upper index are called {\it contravariant}. Their lower-index
 counterparts are called {\it covariant} vectors and are obtained by
 using the Minkowski metric \(g_{\mu \nu}\) according to
 </p>
-<div class="main div" id="org3f1d700">
+<div class="main div" id="orgebe8ad6">
 <p>
 \[
     a_\mu = \sum_{\nu = 0}^3 g_{\mu \nu} a^\nu, \hspace{10mm}
@@ -1678,7 +1682,7 @@ using the Minkowski metric \(g_{\mu \nu}\) according to
 <p>
 \paragraph{Scalar products} are defined as the in-product of covariant/contravariant four-vectors,
 </p>
-<div class="main div" id="org9a2c119">
+<div class="main div" id="org6c9220f">
 <p>
 \[
     \sum_{\mu = 0}^3 a^\mu b_\mu \equiv a^\mu b_\mu
@@ -1738,7 +1742,7 @@ on the same hyperboloid.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_sr_Lt.html b/build/red_sr_Lt.html
index 012b0c2..dc1238f 100644
--- a/build/red_sr_Lt.html
+++ b/build/red_sr_Lt.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1675,7 +1679,7 @@ where \(\bar{d}\) is the distance from \({\cal O}\) to \({\cal A}\) at time
 \]
 Solving these relations yields the dictionary for
 </p>
-<div class="core div" id="org6eadcb7">
+<div class="core div" id="org41fdb3e">
 <p>
 {\bf Lorentz transformations (motion along \(x\) at velocity \(v\))}
 </p>
@@ -1701,7 +1705,7 @@ one can show that velocities add as
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 
diff --git a/build/red_sr_p.html b/build/red_sr_p.html
index addb560..02975fa 100644
--- a/build/red_sr_p.html
+++ b/build/red_sr_p.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-<!-- 2022-02-08 Tue 06:55 -->
+<!-- 2022-02-08 Tue 17:21 -->
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Pre-Quantum Electrodynamics</title>
@@ -272,6 +272,10 @@ Table of contents
 </summary>
 <ul>
 <li>
+<a href="./in_t_l.html#in_t_l">Section and equation labelling</a><span class="headline-id">in.t.l</span>
+
+</li>
+<li>
 <a href="./in_t_c.html#in_t_c">Contextual colors</a><span class="headline-id">in.t.c</span>
 
 </li>
@@ -736,7 +740,7 @@ Table of contents
 
 </li>
 <li>
-<a href="./emsm_esm_d.html#emsm_esm_d">Dielectrics</a><span class="headline-id">emsm.esm.d</span>
+<a href="./emsm_esm_di.html#emsm_esm_di">Dielectrics</a><span class="headline-id">emsm.esm.di</span>
 
 </li>
 <li>
@@ -1653,7 +1657,7 @@ and we get
 \]
 so the time interval in the train is shorter, namely there is a
 </p>
-<div class="core div" id="orgc291303">
+<div class="core div" id="org0aafdf8">
 <p>
 {\bf Time dilation factor}
 \[
@@ -1690,7 +1694,7 @@ and thus
 \]
 Using the time dilation relation then gives
 </p>
-<div class="core div" id="orgb169005">
+<div class="core div" id="org04ef047">
 <p>
 {\bf Lorentz contraction}
 \[
@@ -1710,7 +1714,7 @@ Note that a moving object is only contracted in its direction of motion.
 
 <hr><div id="postamble" class="status">
 <p class="author">Author: Jean-Sébastien Caux</p>
-<p class="date">Created: 2022-02-08 Tue 06:55</p>
+<p class="date">Created: 2022-02-08 Tue 17:21</p>
 <p class="validation"><a href="https://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>