e will be written.  The first
element of the list written will be a two-element list specifying the
index of the start and index of the first character after the end of
the overall substring of the input
string (i.e. the <I>string</I> argument to <B>switch</B>) matched, in a
similar way to the <B>-indices</B> option to the <B><A HREF="regexp.html">regexp</A></B> can
obtain.  Similarly, the second element of the list refers to the first
capturing parenthesis in the regular expression that matched, and so
on.