Delivery point
From Wikipedia, the free encyclopedia
In a postal system, a delivery point (sometimes DP) is a single mailbox or other place at which mail is delivered. It differs from a street address, in that each address may in fact have several delivery points, such as an apartment flat, office department, or other room. Such a building (mainly only residential) is often called a multiple-dwelling unit (MDU) by the USPS.
[edit] United States Postal Service usage
In the US Postal System, delivery point (also abbreviated DPB) is a specific set of digits between 00 and 99 assigned to every official, deliverable address in the United States and its territories served by the USPS. Combined with the ZIP+4 code, this results in a unique, numeric identifier for every address served by the USPS. It is normally encoded in the POSTNET barcode making automated mail sorting possible from a nationwide level all the way down to ordering mail in the order that the postal carrier delivers it (walk sequence.) However, the delivery point is almost never printed in human readable form; as such, it is normally stored separately and usually combined with one more digit called the check digit. This extra digit is used by Barcode Sorters (BCS) to verify the ZIP, ZIP+4, or Delivery Point ZIP code is valid. In a database, storing the ZIP+4 code in a 10 character field (with hyphen) allows easy output in the address block, and combining the check digit in a 3-digit DPB field (instead of calculating it) verifies that the ZIP or DPB have not been changed independently. The delivery point digits (as well as the +4 add on) should always be added/verified using an up-to-date CASS certified program in order to receive the appropriate barcode discount.
In general, since each city block or section of a rural route has a different sub-ZIP (the +4 part), and address numbers generally increase by 100 per block, the DP is the last two digits of most addresses. It may also be the last two digits of a suite number, or the floor number. However, the normal practice in the U.S. is to assign each post office box its own ZIP+4 code; in such cases, the delivery point is redundant.
