6 files changed, 55 insertions, 14 deletions
diff --git a/Master/texmf-dist/source/generic/tex4ht/ChangeLog b/Master/texmf-dist/source/generic/tex4ht/ChangeLog
index 3e15e91edc2..9c755d1d424 100644
--- a/Master/texmf-dist/source/generic/tex4ht/ChangeLog
+++ b/Master/texmf-dist/source/generic/tex4ht/ChangeLog
@@ -1,3 +1,11 @@
+2024-05-20  Michal Hoftich  <michal.h21@gmail.com>
+
+	* tex4ht-4ht.tex (
+	index.4ht, imakeidx.4ht, memoir.4ht, indextools.4ht
+	): added support for optional argument of \index used inside of
+	\caption.
+	https://tex.stackexchange.com/a/718360/2891
+
 2024-05-10  Michal Hoftich  <michal.h21@gmail.com>
 
 	* tex4ht-4ht.tex (lettrine.4ht): defined more keys supported by the
diff --git a/Master/texmf-dist/source/generic/tex4ht/tex4ht-4ht.tex b/Master/texmf-dist/source/generic/tex4ht/tex4ht-4ht.tex
index 040ebf5bde3..c0a300cb012 100644
--- a/Master/texmf-dist/source/generic/tex4ht/tex4ht-4ht.tex
+++ b/Master/texmf-dist/source/generic/tex4ht/tex4ht-4ht.tex
@@ -1,4 +1,4 @@
-% $Id: tex4ht-4ht.tex 1519 2024-05-19 14:40:58Z karl $
+% $Id: tex4ht-4ht.tex 1521 2024-05-20 13:02:00Z michal_h21 $
 % tex tex4ht-4ht   or   ht tex tex4ht-4ht
 %
 % Copyright 2009-2024 TeX Users Group    
@@ -12261,6 +12261,13 @@ and print them when it is safe.
 \ExplSyntaxOff
 >>>
 
+\<latex caption index optional\><<<
+\ExplSyntaxOn
+\renewcommand\:saveindex[2][]{\seq_gput_right:Nn\:savedindex{[#1]{#2}}}
+\def\:printsavedindex{\seq_map_inline:Nn\:savedindex{\index##1}}
+\ExplSyntaxOff
+>>>
+
 \<latex caption index save\><<<
 \:initsaveindex%
 \let\index\:saveindex%
@@ -16518,6 +16525,7 @@ DIV.right
 \<memoir.4ht\><<<
 % memoir.4ht (|version), generated from |jobname.tex
 % Copyright |CopyYear.2003. Eitan M. Gurari
+% Copyright 2003-2024 TeX Users Group
 |<TeX4ht copywrite|>
 \input book.4ht
 \input verse.4ht
@@ -16530,6 +16538,7 @@ DIV.right
    |<memoir 2008|>
    |<mempatch cfg|>
 \fi
+|<latex caption index optional|>
 \Hinput{memoir}
 \endinput
 >>>        \AddFile{8}{memoir}
@@ -32413,6 +32422,7 @@ not necessary in MathML anyway.
 \<index.4ht\><<<
 % index.4ht (|version), generated from |jobname.tex
 % Copyright |CopyYear.1999. Eitan M. Gurari
+% Copyright 2024 TeX Users Group
 |<TeX4ht copywrite|>
 |<index shared|>
 \expandafter\ifx \csname @vwritefile\endcsname\relax
@@ -32420,6 +32430,7 @@ not necessary in MathML anyway.
 \else 
   |<index 3.02|>
 \fi
+|<latex caption index optional|>
 \Hinput{index}
 \endinput
 >>>        \AddFile{7}{index}
@@ -32519,11 +32530,11 @@ multind.sty\EndLink
 
 \<imakeidx.4ht\><<<
 % imakeidx.4ht (|version), generated from |jobname.tex
-% Copyright 2019-2022 TeX Users Group
+% Copyright 2019-2024 TeX Users Group
 |<TeX4ht license text|>
 
 |<imakeidx.sty|>
-
+|<latex caption index optional|>
 
 \Hinput{imakeidx}
 \endinput
@@ -32588,11 +32599,12 @@ d|<haddr prefix|>\last:haddr
 
 \<indextools.4ht\><<<
 % indextools.4ht (|version), generated from |jobname.tex
-% Copyright 2022 TeX Users Group
+% Copyright 2022-2024 TeX Users Group
 |<TeX4ht license text|>
 |<indextools index|>
 |<indextools defs|>
 |<indextools disable options|>
+|<latex caption index optional|>
 
 \Hinput{indextools}
 \endinput
diff --git a/Master/texmf-dist/tex/generic/tex4ht/imakeidx.4ht b/Master/texmf-dist/tex/generic/tex4ht/imakeidx.4ht
index 16af14dc0ea..e6feef1b9a7 100644
--- a/Master/texmf-dist/tex/generic/tex4ht/imakeidx.4ht
+++ b/Master/texmf-dist/tex/generic/tex4ht/imakeidx.4ht
@@ -1,5 +1,5 @@
-% imakeidx.4ht (2022-11-27-07:50), generated from tex4ht-4ht.tex
-% Copyright 2019-2022 TeX Users Group
+% imakeidx.4ht (2024-05-20-13:21), generated from tex4ht-4ht.tex
+% Copyright 2019-2024 TeX Users Group
 %
 % This work may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either
@@ -16,7 +16,7 @@
 %
 % If you modify this program, changing the
 % version identification would be appreciated.
-\immediate\write-1{version 2022-11-27-07:50}
+\immediate\write-1{version 2024-05-20-13:21}
 
 
 \def\:temp#1#2#3{\html:addr%
@@ -34,6 +34,10 @@
 \fi
 \Configure{@begin}{theindex}{\ind:defs\imki@maybeaddtotoc}
 
+\ExplSyntaxOn
+\renewcommand\:saveindex[2][]{\seq_gput_right:Nn\:savedindex{[#1]{#2}}}
+\def\:printsavedindex{\seq_map_inline:Nn\:savedindex{\index##1}}
+\ExplSyntaxOff
 
 
 \Hinput{imakeidx}
diff --git a/Master/texmf-dist/tex/generic/tex4ht/index.4ht b/Master/texmf-dist/tex/generic/tex4ht/index.4ht
index 1e6c2bc82b4..372b7128940 100644
--- a/Master/texmf-dist/tex/generic/tex4ht/index.4ht
+++ b/Master/texmf-dist/tex/generic/tex4ht/index.4ht
@@ -1,5 +1,6 @@
-% index.4ht (2024-04-07-07:55), generated from tex4ht-4ht.tex
+% index.4ht (2024-05-20-13:21), generated from tex4ht-4ht.tex
 % Copyright 1999-2009 Eitan M. Gurari
+% Copyright 2024 TeX Users Group
 % Copyright 2009-2024 TeX Users Group
 %
 % This work may be distributed and/or modified under the
@@ -17,7 +18,7 @@
 %
 % If you modify this program, changing the
 % version identification would be appreciated.
-\immediate\write-1{version 2024-04-07-07:55}
+\immediate\write-1{version 2024-05-20-13:21}
 
 \ifx \a:makeindex\:UnDef
    \NewConfigure{makeindex}{1} \Configure{makeindex}{}
@@ -85,6 +86,11 @@
 }
 
 \fi
+\ExplSyntaxOn
+\renewcommand\:saveindex[2][]{\seq_gput_right:Nn\:savedindex{[#1]{#2}}}
+\def\:printsavedindex{\seq_map_inline:Nn\:savedindex{\index##1}}
+\ExplSyntaxOff
+
 \Hinput{index}
 \endinput
 
diff --git a/Master/texmf-dist/tex/generic/tex4ht/indextools.4ht b/Master/texmf-dist/tex/generic/tex4ht/indextools.4ht
index 75375481b60..cfb361f5de3 100644
--- a/Master/texmf-dist/tex/generic/tex4ht/indextools.4ht
+++ b/Master/texmf-dist/tex/generic/tex4ht/indextools.4ht
@@ -1,5 +1,5 @@
-% indextools.4ht (2022-11-25-13:16), generated from tex4ht-4ht.tex
-% Copyright 2022 TeX Users Group
+% indextools.4ht (2024-05-20-13:21), generated from tex4ht-4ht.tex
+% Copyright 2022-2024 TeX Users Group
 %
 % This work may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either
@@ -16,7 +16,7 @@
 %
 % If you modify this program, changing the
 % version identification would be appreciated.
-\immediate\write-1{version 2022-11-25-13:16}
+\immediate\write-1{version 2024-05-20-13:21}
 
 \def\:tempa[#1]#2{\html:addr%
   \ifindtl@splitindex\else% with splitindex, we would get duplicate index entry destinations
@@ -42,6 +42,11 @@
 \KV@indtl@noautomatictrue
 \indtl@disableautomatictrue
 
+\ExplSyntaxOn
+\renewcommand\:saveindex[2][]{\seq_gput_right:Nn\:savedindex{[#1]{#2}}}
+\def\:printsavedindex{\seq_map_inline:Nn\:savedindex{\index##1}}
+\ExplSyntaxOff
+
 
 \Hinput{indextools}
 \endinput
diff --git a/Master/texmf-dist/tex/generic/tex4ht/memoir.4ht b/Master/texmf-dist/tex/generic/tex4ht/memoir.4ht
index 364a0f85953..e9d47c6ea24 100644
--- a/Master/texmf-dist/tex/generic/tex4ht/memoir.4ht
+++ b/Master/texmf-dist/tex/generic/tex4ht/memoir.4ht
@@ -1,5 +1,6 @@
-% memoir.4ht (2024-01-13-13:40), generated from tex4ht-4ht.tex
+% memoir.4ht (2024-05-20-13:21), generated from tex4ht-4ht.tex
 % Copyright 2003-2009 Eitan M. Gurari
+% Copyright 2003-2024 TeX Users Group
 % Copyright 2009-2024 TeX Users Group
 %
 % This work may be distributed and/or modified under the
@@ -17,7 +18,7 @@
 %
 % If you modify this program, changing the
 % version identification would be appreciated.
-\immediate\write-1{version 2024-01-13-13:40}
+\immediate\write-1{version 2024-05-20-13:21}
 
 \input book.4ht
 \input verse.4ht
@@ -145,6 +146,11 @@
 \fi
 
 \fi
+\ExplSyntaxOn
+\renewcommand\:saveindex[2][]{\seq_gput_right:Nn\:savedindex{[#1]{#2}}}
+\def\:printsavedindex{\seq_map_inline:Nn\:savedindex{\index##1}}
+\ExplSyntaxOff
+
 \Hinput{memoir}
 \endinput