I'd simplify, instead of trying to do it all with a regex.

• Split based on the STARTPRESERVE and STOPPRESERVE markers, stuff the results into an array;
• Do the $text =~ s/\s+/ /g; on the first and last elements of the array; and
• Reassemble using join.

--t. alex

"Nyahhh (munch, munch) What's up, Doc?" --Bugs Bunny