            </p>
                </td>
<td>
                  <p>
                    When set this makes the escape character ordinary inside lists,
                    so that <code class="computeroutput"><span class="special">[\</span><span class="identifier">b</span><span class="special">]</span></code> would match either '\' or 'b'.
                    This bit is on by default for POSIX-Extended regular expressions,
                    but can be unset to force escapes to be recognised inside lists.
 