This is an excerpt from an article published by OFAC:
"Valid OFAC "hits" may need to be blocked or rejected, depending on the nature of the transaction and the applicable regulations. Deciding whether to block or reject can be difficult. Your bank's main compliance responsibility is to ensure that suspect items are interdicted. OFAC will help you determine whether an interdicted transaction ought to be processed, blocked, or rejected."
I've found this to be true that whether something should be blocked or rejected is confusing. Transactions to some countries must be blocked and others must be rejected. Sometimes it isn't so much what type of transaction it is, as where it is going.
I agree that the best way to handle this is to go through OFAC. (If they can give you some guidance as to definitions, be sure to post their response.)