lphabetic character:<tt>[\p{Lower}\p{Upper}]</tt></td></tr>

 <tr><td valign="top" headers="construct posix"><tt>\p{Digit}</tt></td>
     <td headers="matches">A decimal digit: <tt>[0-9]</tt></td></tr>
 <tr><td valign="top" headers="construct posix"><tt>\p{Alnum}</tt></td>
     <td headers="matches">An alphanumeric character:<tt>[\p{Alpha}\p{Digit}]</tt></td></tr>
 <tr><td valign="top" headers="construct posix"><tt>\p{Punct}</tt></td>

     <td headers="matches">Punctuation: One of <tt>!"#$%&'()*+,-./:;<=>?