Your comments

I was thinking of the D ring Binder.... that's where the feature already exists. It would be great to have it for books and magazines as well.
Okay, disregard. I'm so accustomed to seeing the suffixes in the save dialog window I was adding them manually. I do see though that they are added automatically if I don't add them manually. Sorry.
Note: Boxshot 3D had this... I can't find anything comparable in Boxshot 4. (For the record the "manual" and "knowledgebase" on the site are only 5% useful. More documentation would certainly help.)