Index: doc/LaTeXmacros/common.sty
===================================================================
--- doc/LaTeXmacros/common.sty	(revision 7e8db9e0e158e8faa76302965cc9e825c2504486)
+++ doc/LaTeXmacros/common.sty	(revision 1e28e05ba900989f10f4e16a3ef14f7d3e4de9d1)
@@ -11,7 +11,12 @@
 %% Created On       : Sat Apr  9 10:06:17 2016
 %% Last Modified By : Peter A. Buhr
-%% Last Modified On : Wed Mar 19 21:22:28 2025
-%% Update Count     : 664
+%% Last Modified On : Mon May  5 21:37:13 2025
+%% Update Count     : 666
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+% This latex idiom for checking empty optional parameters
+%    \ifx#1\@empty\else\if\relax\detokenize{#1}\relax
+% first checks if there is no optional parameter specified: \name{...} versus \name[]{...}
+% second checks if the optional parameter is specified but empty: \name[]{...} versus \name[...]{...}
 
 \setlength{\textheight}{9in}
@@ -142,7 +147,7 @@
 \newcommand{\Index}{\@ifstar\@sIndex\@Index}
 % inline text and as-in index: \Index[as-is index text]{inline text}
-\newcommand{\@Index}[2][\@empty]{\lowercase{\def\temp{#2}}#2\ifx#1\@empty\index{\temp}\else\index{#1@{\protect#2}}\fi}
+\newcommand{\@Index}[2][\@empty]{\lowercase{\def\temp{#2}}#2\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\index{\temp}\else\index{#1@{\protect#2}}\fi\fi}
 % inline text but index with different as-is text: \Index[index text]{inline text}
-\newcommand{\@sIndex}[2][\@empty]{#2\ifx#1\@empty\index{#2}\else\index{#1@{\protect#2}}\fi}
+\newcommand{\@sIndex}[2][\@empty]{#2\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\index{#2}\else\index{#1@{\protect#2}}\fi\fi}
 
 % inline text and code index (cannot use ©)
@@ -156,6 +161,6 @@
 \newcommand{\newtermFontInline}{\emph}
 \newcommand{\newterm}{\protect\@ifstar\@snewterm\@newterm}
-\newcommand{\@snewterm}[2][\@empty]{{\newtermFontInline{#2}}\ifx#1\@empty\index{#2}\else\index{#1@{\protect#2}}\fi}
-\newcommand{\@newterm}[2][\@empty]{\lowercase{\def\temp{#2}}{\newtermFontInline{#2}}\ifx#1\@empty\index{\temp}\else\index{#1@{\protect#2}}\fi}
+\newcommand{\@snewterm}[2][\@empty]{{\newtermFontInline{#2}}\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\index{#2}\else\index{#1@{\protect#2}}\fi\fi}
+\newcommand{\@newterm}[2][\@empty]{\lowercase{\def\temp{#2}}{\newtermFontInline{#2}}\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\index{\temp}\else\index{#1@{\protect#2}}\fi\fi}
 
 % \snake{<identifier>}
@@ -254,8 +259,8 @@
 \renewcommand{\reftextfaraway}[1]{\unskip, p.~\pageref{#1}}
 \renewcommand{\reftextpagerange}[2]{\unskip, pp.~\pageref{#1}--\pageref{#2}}
-\newcommand{\VRef}[2][Section]{\ifx#1\@empty\else{#1}\nobreakspace\fi\vref{#2}}
-\newcommand{\VRefrange}[3][Sections]{\ifx#1\@empty\else{#1}\nobreakspace\fi\vrefrange{#2}{#3}}
-\newcommand{\VPageref}[2][page]{\ifx#1\@empty\else{#1}\nobreakspace\fi\pageref{#2}}
-\newcommand{\VPagerefrange}[3][pages]{\ifx#1\@empty\else{#1}\nobreakspace\fi\pageref{#2}{#3}}
+\newcommand{\VRef}[2][Section]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else{#1}\nobreakspace\fi\fi\vref{#2}}
+\newcommand{\VRefrange}[3][Sections]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else{#1}\nobreakspace\fi\fi\vrefrange{#2}{#3}}
+\newcommand{\VPageref}[2][page]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else{#1}\nobreakspace\fi\fi\pageref{#2}}
+\newcommand{\VPagerefrange}[3][pages]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else{#1}\nobreakspace\fi\fi\pageref{#2}{#3}}
 
 \let\Oldthebibliography\thebibliography
@@ -282,6 +287,6 @@
 \setlength{\columnposn}{\gcolumnposn}
 \newcommand{\setgcolumn}[1]{\global\gcolumnposn=#1\global\columnposn=\gcolumnposn}
-\newcommand{\C}[2][\@empty]{\ifx#1\@empty\else\global\setlength{\columnposn}{#1}\global\columnposn=\columnposn\fi\hfill\makebox[\textwidth-\columnposn][l]{\LstCommentStyle{#2}}}
-\newcommand{\CD}[2][\@empty]{\ifx#1\@empty\else\global\setlength{\columnposn}{#1}\global\columnposn=\columnposn\fi\hfill\makebox[\textwidth-\columnposn][l]{\LstBasicStyle{#2}}}
+\newcommand{\C}[2][\@empty]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else\global\setlength{\columnposn}{#1}\global\columnposn=\columnposn\fi\fi\hfill\makebox[\textwidth-\columnposn][l]{\LstCommentStyle{#2}}}
+\newcommand{\CD}[2][\@empty]{\ifx#1\@empty\else\if\relax\detokenize{#1}\relax\else\global\setlength{\columnposn}{#1}\global\columnposn=\columnposn\fi\fi\hfill\makebox[\textwidth-\columnposn][l]{\LstBasicStyle{#2}}}
 \newcommand{\CRT}{\global\columnposn=\gcolumnposn}
 
