Those punctuation marks make sense and came from old-old school notations for typewritten manuscripts. I remember them from my Strunck and White /Elements of Style/ book from English 1A (sorta-old-timer here).
Microsoft Office apps still by default apply those marks for you. Quite annoying when you are trying to send an email with a file spec and it bolds things like *suffix.*
Edit: and HN does it as well :)