The following table shows the characters that are matched by the special sets that can be used in regular expressions and Microsoft Word wildcard characters:
| Special Set | Characters matched by the special set |
|---|---|
| [:alpha:] | Any of the characters considered as alphabetic by the operating system under the current ANSI code page. |
| [:alphanum:] | Any of the characters considered as alphanumeric by the operating system under the current ANSI code page. |
| [:control:] | Characters in the hexadecimal range 0x00-0x19. |
| [:digit:] | Any digit from ‘0’ to ‘9’. |
| [:letter:] | Any of the characters considered alphabetic in any language. For example, it matches Thai letters, Greek letters, Hebrew letters, Latin letters, etc. |
| [:letterdigit:] | Any of the characters considered as alphanumeric in any language. |
| [:num:], [:number:] | Any digit from ‘0’ to ‘9’ and the following superscript and fractional numbers: ‘1’, ‘2’, ‘3’, ‘1⁄4’, ‘1⁄2’, ‘3⁄4’ |
| [:punct:], [:punctuation:] | Any of the following characters: ! “ # % & ‘ ( ) * , - . / : ; ? @ [ ] _ { } ¡ « - · » ¿ |
| [:sep:], [:separator:] | Space (Hex 0x20) and non-breakable space (Hex 0xA0) |
| [:symbol:] | Any of the following characters: $ + <=> ^ ` |
| [:space:] | Space (Hex 0x20), tabs and carriage returns in the range Hex 0x09-0x0C, plus Hex 0x85 and Hex 0xA0. |
| [:xdigit:] | Any hexadecimal digit from ‘0’ to ‘9’ and from ‘a’ to ‘f’ (or ‘A’ to ‘F’). |