matches <I>string</I> and no default is given, then the <B>switch</B>
command returns an empty string.
<P>
If the initial arguments to <B>switch</B> start with <B>-</B> then
they are treated as options
unless there are exactly two arguments to <B>switch</B> (in which case the
first must the <I>string</I> and the second must be the
<I>pattern</I>/<I>body</I> list).
The following options are currently supported:
<P>
<DL class="description">
<DT><A NAME="M5"><B>-exact</B></A><DD>
Use exact matching when compar