Editing POSTNET (section)

==Barcode formats==

There have been four formats of Postnet barcodes used by the Postal Service:

A 5 digit (plus check digit) barcode, containing the basic ZIP Code only, referred to as the "A" code.  32 bars total.

A 6 digit (plus check digit) barcode, containing the last 2 digits of the ZIP Code and the 4 digits of the ZIP+4 Code, referred to as a "B" code.  37 bars total. In the early stages of Postal automated mail processing the B code was used to "upgrade" mail that had been coded only with a 5-digit "A" code. This barcode was only found on mail that received a 5-digit barcode on the initial coding by an OCR. Now obsolete.

A 9 digit (plus check digit) barcode, containing the ZIP Code and ZIP+4 Code, referred to as the "C" code. 52 bars total. The 9-digit barcode enabled the sorting of mail to the individual delivery carrier, and in some cases into a semblance of delivery sequence.

An 11 digit (plus check digit) barcode, containing the ZIP Code, ZIP+4 Code, and the [[delivery point]] code. 62 bars total. This is usually referred to as the DPBC, or Delivery Point Bar Code. By including delivery point information, it enables the Postal Service to sort mail into delivery point (address) sequence.<ref>United States Postal Service, Domestic Mail Manual 708.4 - Special Standards, Technical Specifications, Barcoding Standards for Letters and Flats.  {{cite web |url=http://pe.usps.com/cpim/ftp/manuals/dmm300/708.pdf |title=Archived copy |access-date=2010-01-02 |url-status=dead |archive-url=https://web.archive.org/web/20100805234724/http://pe.usps.com/cpim/ftp/manuals/dmm300/708.pdf |archive-date=2010-08-05 }}</ref>