What's "surprising" about the syntax? Or the results for that matter? Looks like a standard ASCII sort to me.

UPDATE: Oops, I replied a bit hastily. I am using 5.6.0 and the "abnormal" behavior does not occur.

Bring out yer dead! Bring out yer dead! I got caught up on the sort behavior and didn't notice the missing value. I have a hunch that guessing games (at least those without a cheat sheet) probably aren't the best way to get things answered though.

--
perl -pew "s/\b;([mnst])/'$1/g"