Payment Terms "Grace Period"

My organization has set up a "grace period" for customers so that there is leeway if "the check is in the mail." For example, if a customer has payment terms of 2% if paid within 30 days, they would be given 40 days and still receive the 2% discount.

A user has asked me where that grace period is set up. I'm new to the A/R module and don't know the answer. I have looked in several places, but none of them seem to be the right place. I found Due Date Rules, but that seems to be used by Advanced Payment Terms. I don't think we use those. My co-worker remembers something about this and is fairly certain it is standard JDE. Can someone help, please?