|.||Matches any character|
|\(||This marks the start of a region for tagging a match.|
|\)||This marks the end of a tagged region.|
|\n||Where n is 1 through 9 refers to the first through ninth tagged region when replacing. For example, if the search string was Fred\([1-9]\)XXX and the replace string was Sam\1YYY, when applied to Fred2XXX this would generate Sam2YYY.|
|\<||This matches the start of a word using Scintilla's definitions of words.|
|\>||This matches the end of a word using Scintilla's definition of words.|
|\x||This allows you to use a character x that would otherwise have a special meaning. For example, \[ would be interpreted as [ and not as the start of a character set.|
|[...]||This indicates a set of characters, for example, [abc] means any of the characters a, b or c. You can also use ranges, for example [a-z] for any lower case character.|
|[^...]||The complement of the characters in the set. For example, [^A-Za-z] means any character except an alphabetic character.|
|^||This matches the start of a line (unless used inside a set, see above).|
|$||This matches the end of a line.|
|*||This matches 0 or more times. For example, Sa*m matches Sm, Sam, Saam, Saaam and so on.|
|+||This matches 1 or more times. For example, Sa+m matches Sam, Saam, Saaam and so on.|
To use text from regular expressions in your replace string you need to use tagged expressions. To include the text of the first tagged expression in your replace text simply include \1. The next tagged expression is \2 and you can use nine tagged expressions in total.
Support for regular expressions in PN2 is currently limited, the supported patterns and syntax are a very small subset of the powerful expressions supported by perl. The biggest restriction is that regular expressions match only within a single line, you cannot use multi-line regular expressions.
There are plans to improve this support by using the PCRE library (used elsewhere in PN2) to provide document searching. If you're interested in helping please make yourself known to the pn-discuss mailing list: PN Mailing Lists.
This documentation needs improving, perhaps you can help?