Explanation of the Residential Delivery File feature used in CODE-1 Plus and Finalist

Products Affected:  CODE-1 Plus, Finalist
The Residential Delivery File (RDI) processing can help you determine the best cost for shipping your packages based upon the fact that some delivery services charge a higher price for delivery to a residential address than they do to a business address. RDI processing can help you shop for the lowest delivery cost for a specific address by identifying 
whether an address is listed as a business or a residential address in the USPS Address Management Systems database.

The Residential Delivery File also provides information regarding business deliveries. The residential status of an input address to which a ZIP+4 CODE is assigned is determined by the fact that it does not match to a record in either RDI table.  RDI will allow you to determine between a residential, business, or mixed (residential and/or business) address.
UPDATED:  November 2, 2017