7.2 Commutative diagrams


Currently it is not possible to support any of the specialist commutative diagram packages as each one causes problems with one or more transformations. Current advice is to use array as in figure 2. However it is acknowledged that labelled diagonal arrows cannot be produced.

The command \PICalt is again providing the full LaTeX  description to the screenreader user as an alt tag. Again, this is likely only to be acceptable for relatively simple diagrams. A side effect of this is that & must not be used directly as this will produce & in xhtml transformed formats and this is a protected character in xhtml. The simplest work round for this is to define, for instance, \tab to be & and use this instead. The commands for producing mappings are cumbersome to read directly and so macros are provided to improve the reading of the raw LaTeX  and hence also the alt tag.

This below must contain a full begin and end math environment otherwise the transformation of the alt tag is not completed correctly resulting in no output for the entire transformation.

\begin{equation*} \begin{array}{ccc} A& {\stackrel{f}{\longrightarrow }} & B \\ \Big\downarrow {\scriptstyle {g}} & & \Big\downarrow {\scriptstyle {g’}} \\ A^* & {\stackrel{f^*}{\longrightarrow }} & B^* \end{array}\end{equation*}

Figure 2: Commuting diagram