Document how to solicit copyright forms in START

Unless I have overlooked something, there is no documentation in ACLPUB concerning how to configure the paper submission form in one's START event in such a way that ACLPUB can later find and process the copyright forms using its Generate -> Copyright Signatures function. Is it sufficient to configure the submission page to accept an "Additional Attachment"? If so, is there a particular value we need to enter in the "What to call this document" field? It would be nice if this were documented.