I've installed mIRC6.31 (haven't ever used the 6.3) and started reading the help file.
I think there's an error or instead, a misunderstanding statement on the page discussing about Regular Expressions.
The help file says:
$regex([name], text, re)
Returns N, the number of strings in text that matched the regular expression.
That's false and should be imo:
Returns 0 or 1 on whether the regular expression didn't match or matched 'text'. (or something like that)
However, the statement of the help file refers to the /g modifier. Maybe this should be documented or modified.
There's the same issue for $regsub.
$regsub([name], text, re, subtext, %var)
Performs a regular expression match, like $regex(), and then performs a substitution using subtext.
Returns N, the number of substitutions made, and assigns the result to %var.
Again, that's true if and only the /g modifier is included.
Regards