What is a reversed comma?

There's no such thing as a "reversed comma" in standard English punctuation.

Here's why:

* Commas (,) are used for specific grammatical purposes like separating items in a list, marking off introductory phrases, or setting off non-essential clauses. They always have the same shape.

* Apostrophes (') might be what you're thinking of. They are used for contractions (can't, shouldn't), possessives (the dog's bone), and sometimes for plurals of letters (A's, 1980's). They look like a comma turned 90 degrees.

Let me know if you were thinking of something else, or if you have a specific example in mind. I'm happy to help!