From National Government Services, Inc., Corporate Communications:
A change has been made to the Billing Provider Address for 5010. The Billing Provider Address (2010AA loop) will require a physical location address to be reported. P.O. Box and lockbox addresses cannot be reported as a Billing Provider Address. If you would like to send a P.O. Box or lockbox address, it must be reported as a Pay-To Address (2010AB loop). The Pay-To Address is only needed if it is different than the one being used for the Billing Provider.
Providers should work with their software vendors to ensure that the correct addresses are captured and sent in the correct locations when they make the transition to sending the 5010 format.