nstruct posix"><tt>\p{Blank}</tt></td>
     <td headers="matches">A space or a tab: <tt>[ \t]</tt></td></tr>
 <tr><td valign="top" headers="construct posix"><tt>\p{Cntrl}</tt></td>
     <td headers="matches">A control character: <tt>[\x00-\x1F\x7F]</td></tr>

 <tr><td valign="top" headers="construct posix"><tt>\p{XDigit}</tt></td>
     <td headers="matches">A hexadecimal digit: <tt>[0-9a-fA-F]</tt></td></tr>
 <tr><td valign="top" headers="construct posix"><tt>\p{Space}</tt></td>
     <td headers="matches">A