[[!comment format=mdwn
 username="joey"
 subject="""comment 25"""
 date="2018-09-24T15:42:24Z"
 content="""
@Ilya_Shlyakhter, it's a heuristic, what consititues a file extension is
not very well defined (consider ".tar.gz" and ".not-an-extension").
The heuristic has been refined over the years, but will never be perfect.
But, I don't know of any 5+ character file extensions in common use!
"""]]