(serious) the upload page would seem the most obvious place to note what & what cannot be uploaded & to which gallery...
the checks in place to make sure it's understood...
& maybe available in several languages?

(not so serious ;) once all the upload checkpoints have been passed, appropriate accompanying text & proper credit given & run through a scan & promise of first born made, then & only then, if they're still so inclined... can a member post...
whew!