\end{prog}
for each of $C$'s superclasses $A$ in the same chain in some (unimportant)
order. The (somewhat obtuse) purpose of this union is to engage the `common
-initial sequence' rule of \cite[6.5.2.3]{ISO:1990:IIP,ANSI:1999:AII}.
+initial sequence' rule of \cite[6.5.2.3]{iso-1990:c,ansi-1999:c}.
\subsubsection{The ichain structure}
The @|ichain| structure contains (in order), a pointer