POSIX       trad. Perl  utf8 Perl

 [:^digit:]      \D      \P{IsDigit}
 [:^space:]      \S      \P{IsSpace}
 [:^word:]       \W      \P{IsWord}

##</code><code>##

See the utf8 manpage for details about `\pP', `\PP', and `\X'.

##</code><code>##

·   Named Unicode properties and block ranges make be used
    as character classes via the new `\p{}' (matches
    property) and `\P{}' (doesn't match property)
    constructs.  For instance, `\p{Lu}' matches any
    character with the Unicode uppercase property, while
    `\p{M}' matches any mark character.  Single letter
    properties may omit the brackets, so that can be
    written `\pM' also.  Many predefined character classes
    are available, such as `\p{IsMirrored}' and
    `\p{InTibetan}'.