You might have noticed that the name of this little web space is “P.F. Hawkins’s Tilde Site”. For some reason, when I set this up, I decided to add the ess after the possessive apostrophe. It is not strictly necessary. In other times and places I have used P.F. Hawkins’ to indicate that something is mine.
Strunk & White swear by the extra apostrophe. I don’t. I am surprised I included it. But I don’t know what I’d gain by removing it now. Other than dishonoring Strunk & White. Which I have no problem doing; their writing advice is a hot mess.