In the Charybdis family tree of IRCd's (which is a fork from Ratbox, la Hybrid) they call this extension EXTBAN.

Code:
:hobana.freenode.net 005 Raccoon EXTBAN=$,ajrxz 

-> Server: help extban
-
extban MODE <channel> <+|-><b|q|e|I> $[~]<type>[:<data>]
extban  
extban Extended bans (ban conditionals) allow different checks than the usual
extban nick!user@host or nick!user@ip match to determine whether someone should
extban be banned, quieted, exempted or invited.
extban  
extban Extended bans are of the form $[~]<type>[:<data>]. The <type> is one
extban character (case insensitive) and determines the type of match. Most types
extban allow or require an extra field <data>. If the tilde (~) is present, the
extban result of the comparison will be negated, unless the ban is invalid in which
extban case it will never match. Invalid bans are ones where <data> is missing but
extban required or where <data> is otherwise invalid as noted below.
extban  
extban Unless noted below, all types can be used with +b, +q, +e and +I.
extban  
extban  extb Type  - DESCRIPTION
extban ------------------------------------------------------------------------
extban      $a     - Matches all logged in users
extban   $a:<mask> - Matches users logged in with a username matching the mask
extban               (* and ? wildcards)
extban   $c:<chan> - Matches users who are on the given channel; this is only
extban               valid if the channel exists and is not +s or +p. (The ops
extban               of the channel the ban is on cannot necessarily see whether
extban               the user is in the target channel, so it should not
extban               influence whether they can join either.)
extban      $o     - Matches opers (most useful with +I)
extban   $r:<mask> - Matches users with a realname (gecos) matching the mask
extban               (* and ? wildcards); this can only be used with +b and +q
extban   $s:<mask> - matches users connected to a server matching the mask
extban               (* and ? wildcards); this can only be used with +b and +q
extban   $j:<chan> - matches users who are or are not banned from a specified
extban               channel
extban   $x:<mask> - Bans all users with matching nick!user@host#gecos
extban      $z     - Matches all SSL users
extban  
extban End of /HELP.

I understand this help may be missing one or two.

Also, there have been no breaks or faults in mIRC for years and years, and nobody honestly expects you to add support for these. I don't think any client scripting language automatically does. I mean, maybe $a:<account> and $a and $~a would be doable. Seems a bit far out there.

Well. At least I won lunch.
Good philosophy, see good in bad, I like!