Editing POSTNET (section)

{{Short description|US Postal Service barcode symbology}}
{{Other uses|Postnet (disambiguation)}}
{| class="wikitable" style="float:right; margin-left:1ex;"
! Value !! Encoding
|-
|align=center| 1 ||align=center| [[Image:POSTNET 1.svg]]
|-
|align=center| 2 ||align=center| [[Image:POSTNET 2.svg]]
|-
|align=center| 3 ||align=center| [[Image:POSTNET 3.svg]]
|-
|align=center| 4 ||align=center| [[Image:POSTNET 4.svg]]
|-
|align=center| 5 ||align=center| [[Image:POSTNET 5.svg]]
|-
|align=center| 6 ||align=center| [[Image:POSTNET 6.svg]]
|-
|align=center| 7 ||align=center| [[Image:POSTNET 7.svg]]
|-
|align=center| 8 ||align=center| [[Image:POSTNET 8.svg]]
|-
|align=center| 9 ||align=center| [[Image:POSTNET 9.svg]]
|-
|align=center| 0 ||align=center| [[Image:POSTNET 0.svg]]
|}

'''POSTNET''' ('''Post'''al '''N'''umeric '''E'''ncoding '''T'''echnique) is a [[barcode]] [[symbology]] used by the [[United States Postal Service]] to assist in directing mail.  The [[ZIP Code]] or ZIP+4 code is encoded in half- and full-height bars.<ref>{{cite book|title=Publication 25, Designing Letter and Reply Mail|date=July 2003|publisher=United States Postal Service|location=United States|url=http://www.siemons.com/forms/pdf/designing_letter_reply_mail.pdf|pages=37–56|archive-url=https://web.archive.org/web/20050118015758/http://www.siemons.com/forms/pdf/designing_letter_reply_mail.pdf|archive-date=2005-01-18}}</ref>  Most often, the [[delivery point]] is added, usually being the last two [[numerical digit|digit]]s of the [[address (geography)|address]] or [[Post office box|PO box]] number.

The barcode starts and ends with a full bar (often called a guard rail or frame bar and represented as the letter "S" in one version of the [[USPS]] [[TrueType Font]]) and has a [[check digit]] after the ZIP, ZIP+4, or delivery point.  The encoding table is shown on the right.

Each individual digit is represented by a set of five bars, two of which are full bars (i.e. [[two-out-of-five code]]). The full bars represent "on" bits in a pseudo-[[binary code]] in which the places represent, from left to right: 7, 4, 2, 1, and 0.  (Though in this scheme, [[0 (number)|zero]] is encoded as 11 in [[decimal]], or in POSTNET "binary" as 11000<!-- This is correct; 7+4+0+0+0 = 11-->.)