The regular expression extension was in the pre-BASE/Extension split, and was later marked as “rejected”, specifically because my post about how you could abuse regular expressions. (My post; https://dcpp.wordpress.com/2008/07/22/denial-of-service-id-like-one-please)
So that no one uses the same FCC or field for something else, I want to reserve REGX (and RX) here.
Actually, if someone do indeed implement this feature, it is your prerogative and I will as such add it to that coming ADC-Ext revision.
=== Regular expressions in SCH
This extension will add Perl’s regular expressions (> http://perldoc.perl.org/perlre.html> ) with full Unicode support to SCH.
Signal REGX in SUP and in the INF’s SU field.
|RE |Regular expression according to > http://perldoc.perl.org/perlre.html