From original "Anonymous Monk" ... it appears that the $dle is interpolated within the character class and works as intended ! Is there anything to disuade me from the original construction ?

It appears that variables (e.g. $dle) are interpolated within character classes  (e.g. [$dle])but not within hex character specifications (e.g \x{$dle}). Is there a reference source that makes this kind of information clear ? I have "Programming Perl", "Learning Perl", and "Perl Cookbook", but I didn't find it in those ... Thanks, Scott.