Prepare for future use of \subfloat

The most important part here is probably making other authors aware of the current LaTeXML issues when combined with \autoref.

chapters/synchronous.tex

@@ -184,6 +184,16 @@ \section{Definitions}\doublelabel{definitions}
 
 \subsection{Clocks and Clocked Variables}\doublelabel{clocks-and-clocked-variables}
 
+% We can't use \subfloat just yet due to LaTeXML issue:
+%   https://github.com/brucemiller/LaTeXML/issues/1292
+%\begin{figure}[tb]
+%  \centering
+%  \subfloat[A piecewise-constant variable.]{\includegraphics[width=5cm]{piecewise}\doublelabel{fig:piecewise-constant-variable}}
+%  \subfloat[A clock variable.]{\includegraphics[width=5cm]{clock}\doublelabel{fig:clock-variable}}
+%  \subfloat[A clocked variable.]{\includegraphics[width=5cm]{clocked}\doublelabel{fig:clocked-variable}}
+%  \caption{The different kinds of discrete-time variables.  The \lstinline!hold! extrapolation of the clocked variable is illustrated with dashed green lines.}
+%\end{figure}
+
 In \autoref{discrete-time-expressions} the term \emph{discrete-time} Modelica expression and in \autoref{continuous-time-expressions} the term \emph{continuous-time} Modelica expression is defined.
 In this chapter, two additional kinds of discrete-time expressions/variables are defined that are associated to clocks and are therefore called \firstuse{clocked discrete-time} expressions.  The
 different kinds of discrete-time variables in Modelica are defined below.

preamble.tex

@@ -39,6 +39,12 @@
 \graphicspath{{media/}{../media/}} % so that chapter files can also find the images
 \def\figureautorefname{figure} % Use lower case initial, just like for sections.
 
+% Don't use subfig.sty until this LaTeXML issue has been fixed:
+% - https://github.com/brucemiller/LaTeXML/issues/1292
+% Leaving commented-out code as a hint to anyone who considers using subfig.
+%\usepackage{subfig}
+%\newcommand{\subfigureautorefname}{\figureautorefname}
+
 \usepackage{verbatim}
 % The fixltx2e that was used for textsubscript is no longer needed for pdf, but is needed by latexml
 \ifpdf