The asterisk represents any number of integers, including zero. The question mark represents any single integer. So assuming a path which looks like {0;1;2}, you’ll get a match with {?;?;?} and with {?;?;2} but not with {?;?}.
When using asterisks, you have a lot more flexibility. {*} will match any imaginable path. {*;2} will match any path ending in 2. {*;2;*} will match any path containing 2, even if it only starts or ends with a 2.