diff --git a/doc/Doxygen/README.html b/doc/Doxygen/README.html
index 1804b7f393..b6fc1f794d 100644
--- a/doc/Doxygen/README.html
+++ b/doc/Doxygen/README.html
@@ -3,22 +3,29 @@
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
+<!-- 2023-07-11 Tue 16:44 -->
+<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
+<meta name="viewport" content="width=device-width, initial-scale=1" />
 <title>Building the Doxygen help for OpenFOAM</title>
-<!-- 2016-06-18 Sat 10:13 -->
-<meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
-<meta  name="generator" content="Org-mode" />
+<meta name="generator" content="Org mode" />
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-  .title  { text-align: center; }
+  .title  { text-align: center;
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+              font-size: medium;
+              font-weight: bold;
+              margin-top:0; }
   .todo   { font-family: monospace; color: red; }
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+  .done   { font-family: monospace; color: green; }
+  .priority { font-family: monospace; color: orange; }
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   .timestamp { color: #bebebe; }
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-  .right  { margin-left: auto; margin-right: 0px;  text-align: right; }
-  .left   { margin-left: 0px;  margin-right: auto; text-align: left; }
-  .center { margin-left: auto; margin-right: auto; text-align: center; }
+  .org-right  { margin-left: auto; margin-right: 0px;  text-align: right; }
+  .org-left   { margin-left: 0px;  margin-right: auto; text-align: left; }
+  .org-center { margin-left: auto; margin-right: auto; text-align: center; }
   .underline { text-decoration: underline; }
   #postamble p, #preamble p { font-size: 90%; margin: .2em; }
   p.verse { margin-left: 3%; }
@@ -45,27 +52,111 @@
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+  pre.src-dot:before { content: 'Graphviz'; }
+  pre.src-calc:before { content: 'Emacs Calc'; }
   pre.src-emacs-lisp:before { content: 'Emacs Lisp'; }
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-  pre.src-java:before  { content: 'Java'; }
-  pre.src-sql:before   { content: 'SQL'; }
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+  pre.src-hledger:before { content: 'hledger'; }
+  pre.src-java:before { content: 'Java'; }
+  pre.src-js:before { content: 'Javascript'; }
+  pre.src-latex:before { content: 'LaTeX'; }
+  pre.src-ledger:before { content: 'Ledger'; }
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+  pre.src-lilypond:before { content: 'Lilypond'; }
+  pre.src-lua:before { content: 'Lua'; }
+  pre.src-matlab:before { content: 'MATLAB'; }
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+  pre.src-python:before { content: 'Python'; }
+  pre.src-R:before { content: 'R'; }
+  pre.src-ruby:before { content: 'Ruby'; }
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+  pre.src-sql:before { content: 'SQL'; }
+  pre.src-sqlite:before { content: 'SQLite'; }
+  /* additional languages in org.el's org-babel-load-languages alist */
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+  pre.src-J:before { content: 'J'; }
+  pre.src-makefile:before { content: 'Makefile'; }
+  pre.src-maxima:before { content: 'Maxima'; }
+  pre.src-perl:before { content: 'Perl'; }
+  pre.src-picolisp:before { content: 'Pico Lisp'; }
+  pre.src-scala:before { content: 'Scala'; }
+  pre.src-shell:before { content: 'Shell Script'; }
+  pre.src-ebnf2ps:before { content: 'ebfn2ps'; }
+  /* additional language identifiers per "defun org-babel-execute"
+       in ob-*.el */
+  pre.src-cpp:before  { content: 'C++'; }
+  pre.src-abc:before  { content: 'ABC'; }
+  pre.src-coq:before  { content: 'Coq'; }
+  pre.src-groovy:before  { content: 'Groovy'; }
+  /* additional language identifiers from org-babel-shell-names in
+     ob-shell.el: ob-shell is the only babel language using a lambda to put
+     the execution function name together. */
+  pre.src-bash:before  { content: 'bash'; }
+  pre.src-csh:before  { content: 'csh'; }
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+  /* Additional Emacs modes also supported by the LaTeX listings package */
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+  pre.src-asm:before { content: 'Assembler'; }
+  pre.src-caml:before { content: 'Caml'; }
+  pre.src-delphi:before { content: 'Delphi'; }
+  pre.src-html:before { content: 'HTML'; }
+  pre.src-idl:before { content: 'IDL'; }
+  pre.src-mercury:before { content: 'Mercury'; }
+  pre.src-metapost:before { content: 'MetaPost'; }
+  pre.src-modula-2:before { content: 'Modula-2'; }
+  pre.src-pascal:before { content: 'Pascal'; }
+  pre.src-ps:before { content: 'PostScript'; }
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+  pre.src-simula:before { content: 'Simula'; }
+  pre.src-tcl:before { content: 'tcl'; }
+  pre.src-tex:before { content: 'TeX'; }
+  pre.src-plain-tex:before { content: 'Plain TeX'; }
+  pre.src-verilog:before { content: 'Verilog'; }
+  pre.src-vhdl:before { content: 'VHDL'; }
+  pre.src-xml:before { content: 'XML'; }
+  pre.src-nxml:before { content: 'XML'; }
+  /* add a generic configuration mode; LaTeX export needs an additional
+     (add-to-list 'org-latex-listings-langs '(conf " ")) in .emacs */
+  pre.src-conf:before { content: 'Configuration File'; }
 
   table { border-collapse:collapse; }
   caption.t-above { caption-side: top; }
   caption.t-bottom { caption-side: bottom; }
   td, th { vertical-align:top;  }
-  th.right  { text-align: center;  }
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-  th.center { text-align: center; }
-  td.right  { text-align: right;  }
-  td.left   { text-align: left;   }
-  td.center { text-align: center; }
+  th.org-right  { text-align: center;  }
+  th.org-left   { text-align: center;   }
+  th.org-center { text-align: center; }
+  td.org-right  { text-align: right;  }
+  td.org-left   { text-align: left;   }
+  td.org-center { text-align: center; }
   dt { font-weight: bold; }
-  .footpara:nth-child(2) { display: inline; }
-  .footpara { display: block; }
+  .footpara { display: inline; }
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@@ -85,6 +176,7 @@
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   .org-info-js_search-highlight
     { background-color: #ffff00; color: #000000; font-weight: bold; }
+  .org-svg { width: 90%; }
   /*]]>*/-->
 </style>
 <script type="text/javascript">
@@ -92,7 +184,7 @@
 @licstart  The following is the entire license notice for the
 JavaScript code in this tag.
 
-Copyright (C) 2012-2013 Free Software Foundation, Inc.
+Copyright (C) 2012-2019 Free Software Foundation, Inc.
 
 The JavaScript code in this tag is free software: you can
 redistribute it and/or modify it under the terms of the GNU
@@ -133,6 +225,28 @@ for the JavaScript code in this tag.
  }
 /*]]>*///-->
 </script>
+<script type="text/x-mathjax-config">
+    MathJax.Hub.Config({
+        displayAlign: "center",
+        displayIndent: "0em",
+
+        "HTML-CSS": { scale: 100,
+                        linebreaks: { automatic: "false" },
+                        webFont: "TeX"
+                       },
+        SVG: {scale: 100,
+              linebreaks: { automatic: "false" },
+              font: "TeX"},
+        NativeMML: {scale: 100},
+        TeX: { equationNumbers: {autoNumber: "AMS"},
+               MultLineWidth: "85%",
+               TagSide: "right",
+               TagIndent: ".8em"
+             }
+});
+</script>
+<script type="text/javascript"
+        src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_HTML"></script>
 </head>
 <body>
 <div id="content">
@@ -141,15 +255,15 @@ for the JavaScript code in this tag.
 <h2>Table of Contents</h2>
 <div id="text-table-of-contents">
 <ul>
-<li><a href="#sec-1">1. Doxygen</a></li>
-<li><a href="#sec-2">2. Configuration</a></li>
-<li><a href="#sec-3">3. Running Doxygen</a></li>
+<li><a href="#org82328a7">1. Doxygen</a></li>
+<li><a href="#orgb35a0b8">2. Configuration</a></li>
+<li><a href="#orgadf2d2f">3. Running Doxygen</a></li>
 </ul>
 </div>
 </div>
 
-<div id="outline-container-sec-1" class="outline-2">
-<h2 id="sec-1"><span class="section-number-2">1</span> Doxygen</h2>
+<div id="outline-container-org82328a7" class="outline-2">
+<h2 id="org82328a7"><span class="section-number-2">1</span> Doxygen</h2>
 <div class="outline-text-2" id="text-1">
 <p>
 The HTML documentation of OpenFOAM can be built using the Doxygen software.
@@ -158,9 +272,9 @@ graphviz software package.  To build the documentation on the Ubuntu GNU/Linux
 system, for example, the user should install both <code>doxygen</code> and <code>graphviz</code>
 packages, e.g. by typing in a terminal window:
 </p>
+
 <ul class="org-ul">
-<li><code>sudo apt-get install doxygen graphviz</code>
-</li>
+<li><code>sudo apt-get install doxygen graphviz</code></li>
 </ul>
 
 <p>
@@ -172,20 +286,20 @@ permission for the directory that Doxygen writes files to.
 </div>
 </div>
 
-<div id="outline-container-sec-2" class="outline-2">
-<h2 id="sec-2"><span class="section-number-2">2</span> Configuration</h2>
+<div id="outline-container-orgb35a0b8" class="outline-2">
+<h2 id="orgb35a0b8"><span class="section-number-2">2</span> Configuration</h2>
 <div class="outline-text-2" id="text-2">
 <p>
-The Doygen configuration file, Doxyfile, in the <code>$WM_PROJECT_DIR/doc/Doxygen</code>
+The Doxygen configuration file, Doxyfile, in the <code>$WM_PROJECT_DIR/doc/Doxygen</code>
 directory is configured to work with Doxygen versions 1.6.3-1.8.5.
 </p>
 
 <p>
 The Header, Footer, and Stylesheet are generated automatically:
 </p>
+
 <ul class="org-ul">
-<li><code>doxygen -w html header.html footer.html customdoxygen.css</code>
-</li>
+<li><code>doxygen -w html header.html footer.html customdoxygen.css</code></li>
 </ul>
 
 <p>
@@ -194,33 +308,30 @@ See: <a href="https://www.stack.nl/~dimitri/doxygen/manual/customize.html">https
 </div>
 </div>
 
-<div id="outline-container-sec-3" class="outline-2">
-<h2 id="sec-3"><span class="section-number-2">3</span> Running Doxygen</h2>
+<div id="outline-container-orgadf2d2f" class="outline-2">
+<h2 id="orgadf2d2f"><span class="section-number-2">3</span> Running Doxygen</h2>
 <div class="outline-text-2" id="text-3">
 <p>
 In the <code>$WM_PROJECT_DIR/doc/Doxygen</code> directory type
 </p>
 <ul class="org-ul">
-<li><code>./Allwmake</code>
-</li>
+<li><code>./Allwmake</code></li>
 </ul>
 
 <p>
 which will generate the <code>$WM_PROJECT_DIR/doc/Doxygen/html</code> directory
 containing the OpenFOAM source code documentation.  Load the <code>index.html</code> file
-into a browser, <i>e.g.</i>
+into a browser, \e.g.\
 </p>
 <ul class="org-ul">
-<li><code>firefox $WM_PROJECT_DIR/doc/Doxygen/html/index.html</code>
-</li>
+<li><code>firefox html/index.html</code></li>
 </ul>
 </div>
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Date: 18th June 2016</p>
-<p class="date">Created: 2016-06-18 Sat 10:13</p>
-<p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 24.5 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
+<p class="date">Date: 11nd June 2023</p>
+<p class="date">Created: 2023-07-11 Tue 16:44</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
 </body>
diff --git a/doc/Doxygen/README.org b/doc/Doxygen/README.org
index 07568578a4..eb22760aec 100644
--- a/doc/Doxygen/README.org
+++ b/doc/Doxygen/README.org
@@ -2,10 +2,10 @@
 #
 #+TITLE:         Building the Doxygen help for OpenFOAM
 #+AUTHOR:               The OpenFOAM Foundation
-#+DATE:                     18th June 2016
+#+DATE:                     11nd June 2023
 #+LINK:                  http://www.openfoam.org
 #+OPTIONS: author:nil ^:{}
-# Copyright (c) 2015-2016 OpenFOAM Foundation.
+# Copyright (c) 2015-2023 OpenFOAM Foundation.
 
 * Doxygen
   The HTML documentation of OpenFOAM can be built using the Doxygen software.
@@ -22,7 +22,7 @@
   permission for the directory that Doxygen writes files to.
 
 * Configuration
-  The Doygen configuration file, Doxyfile, in the =$WM_PROJECT_DIR/doc/Doxygen=
+  The Doxygen configuration file, Doxyfile, in the =$WM_PROJECT_DIR/doc/Doxygen=
   directory is configured to work with Doxygen versions 1.6.3-1.8.5.
 
   The Header, Footer, and Stylesheet are generated automatically:
