There’s an Epicor white paper on it. I’ll look for it.
I’d say there’s a few that should be ABSOLUTLEY avoided: ' (the foot mark), " (the inch mark), and (space), and any other characters a potential Barcode format might use.
Avoid the space character, as its easy to put an em space in when copying and pasting from a website. Or even if someone uses MS Word to convey the “part number”. Same for the “em dash” too.