If the rate lock date for a particular loan is not available in the APOR table, you use the most recent date prior to the rate lock date, is that correct? Don't deal with this much, so want to make sure. Thanks.

Correct, the APOR table is typically updated every Monday and is 'current' through the week or until the next update is published. For example, if you have a 11/29 rate lock, the 11/25 rate would have been in effect at the time the rate was locked and is the correct comparable rate.