3 files changed, 20 insertions, 3 deletions
diff --git a/support/TeX4ht/source/Makefile b/support/TeX4ht/source/Makefile
index 825444558f..4c80ac5662 100644
--- a/support/TeX4ht/source/Makefile
+++ b/support/TeX4ht/source/Makefile
@@ -1,4 +1,4 @@
-# $Id: Makefile 1173 2022-07-07 13:29:07Z michal_h21 $
+# $Id: Makefile 1186 2022-08-17 21:26:24Z karl $
 # This file is public domain.  Originally written 2010, Karl Berry.
 # Assumes GNU make.
 
diff --git a/support/TeX4ht/source/tex4ht-4ht.tex b/support/TeX4ht/source/tex4ht-4ht.tex
index 07e8f85b21..c5db34f788 100644
--- a/support/TeX4ht/source/tex4ht-4ht.tex
+++ b/support/TeX4ht/source/tex4ht-4ht.tex
@@ -1,4 +1,4 @@
-% $Id: tex4ht-4ht.tex 1184 2022-08-17 11:45:35Z michal_h21 $
+% $Id: tex4ht-4ht.tex 1186 2022-08-17 21:26:24Z karl $
 % tex tex4ht-4ht   or   ht tex tex4ht-4ht
 %
 % Copyright 2009-2022 TeX Users Group    
diff --git a/support/TeX4ht/source/tex4ht-mathml.tex b/support/TeX4ht/source/tex4ht-mathml.tex
index f16d7c5f96..b2e07b052e 100644
--- a/support/TeX4ht/source/tex4ht-mathml.tex
+++ b/support/TeX4ht/source/tex4ht-mathml.tex
@@ -1,4 +1,4 @@
-% $Id: tex4ht-mathml.tex 1180 2022-07-26 08:09:24Z michal_h21 $$
+% $Id: tex4ht-mathml.tex 1183 2022-08-17 10:03:42Z michal_h21 $$
 % compile 3 times: latex tex4ht-mathltx
 %           or   xhlatex tex4ht-mathltx "html,3,sections+"
 %
@@ -102,6 +102,7 @@
 
 
 \<amsmath html-mml pre 2000\><<<
+% pre 2000
 \Configure{equation}
   {\ifvmode \IgnorePar\fi \EndP
    \HCode{<table class="equation"><tr><td>}%
@@ -123,6 +124,7 @@
 
 
 \<amsmath html-mml jan 2000\><<<
+% jan 2000
 \Configure{equation}
   {\ifvmode \IgnorePar\fi \EndP
    \HCode{<table class="equation"><tr><td>}%
@@ -148,11 +150,14 @@
 
 
 \<amsmath html-mml july 2000\><<<
+% and here it should be
+|<alt mathopen for eq|>
 \Configure{equation}
   {\ifvmode \IgnorePar\fi\EndP
    \HCode{<table class="equation"><tr><td>}%
    |<amsmath equation july 2000|>%
    |<math display in equation|>%
+   |<mathopen in equation|>
   }
   {\ifvmode \IgnorePar\fi\EndP
    \HCode{</td><td class="eq-no">}%
@@ -176,11 +181,23 @@
    
 
 
+
 \<amsmath equation jan 2000\><<<
 |<amsmath equation july 2000|>%
 >>>
 
+Current AMSMath uses empty mathopen at the beginning of an equation, 
+which results in missing markup for subsequent numbers and characters.
+
+We check for empty parameter, and don't execute configurations when it is empty.
 
+\<alt mathopen for eq\><<<
+\def\eq:mathopen#1{\ifx\relax#1\relax\else\a:mathopen\fi\o:mathopen:{#1}}
+>>>
+
+\<mathopen in equation\><<<
+\let\mathopen\eq:mathopen%
+>>>