Gee, I don't know, how many 'regexes' are there? The only Regex I know about is used for searching complex patterns in text/strings, say to check if a string input is in the right format, i.e. [0-9A-Za-z]{6,}@[a-z0-9].(com|org) for e-mail addresses, [ABCDEFGH][12345678] for chess board tiles. All I see in the system expressions/system conditions regarding text/strings are just common string operations.