$s = '<COMMA>pre-stuff<EXHIBITING>some stuff</EXHIBITING>post-stuff</COMMA>';;

print "$1 :: $2" while $s =~ s[<(\D+)>([^<]*?)</\1>][]gi;;
EXHIBITING :: some stuff
COMMA :: pre-stuffpost-stuff

##</code><code>##

$s = '<COMMA>pre-stuff<EXHIBITING>some <= stuff</EXHIBITING>post-stuff</COMMA>';;

print "$1 :: $2" while $s =~ s[<(\D+)>([^<]*?)</\1>][]gi;;
{zilch here}