POSTNET - AbsoluteAstronomy.com

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POSTNET (Postal Numeric Encoding Technique) is a barcode

Barcode

A barcode is an optical machine-readable representation of data, which shows data about the object to which it attaches. Originally barcodes represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or 1 dimensional . Later they evolved into rectangles,...

symbology

Symbology

Symbology concerns the study of symbols.Symbology may also refer to:-Academics:* Semiotics, study of signs and symbols* Iconography, branch of art history which studies images...

that was used by the United States Postal Service

United States Postal Service

The United States Postal Service is an independent agency of the United States government responsible for providing postal service in the United States...

to assist in directing mail. The ZIP Code

ZIP Code

ZIP codes are a system of postal codes used by the United States Postal Service since 1963. The term ZIP, an acronym for Zone Improvement Plan, is properly written in capital letters and was chosen to suggest that the mail travels more efficiently, and therefore more quickly, when senders use the...

or ZIP+4 code is encoded in half- and full-height bars. Most often, the delivery point

Delivery point

In a postal system, a delivery point 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...

is added, usually being the last two digit

Numerical digit

A digit is a symbol used in combinations to represent numbers in positional numeral systems. The name "digit" comes from the fact that the 10 digits of the hands correspond to the 10 symbols of the common base 10 number system, i.e...

s of the address

Address (geography)

An address is a collection of information, presented in a mostly fixed format, used for describing the location of a building, apartment, or other structure or a plot of land, generally using political boundaries and street names as references, along with other identifiers such as house or...

or PO box

Post Office box

A post-office box or Post Office box is a uniquely addressable lockable box located on the premises of a post office station....

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

Check digit

A check digit is a form of redundancy check used for error detection, the decimal equivalent of a binary checksum. It consists of a single digit computed from the other digits in the message....

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

Two-out-of-five code

In telecommunication, a two-out-of-five code is an m of n code that provides exactly ten possible combinations, and thus is popular for representing decimal digits using five bits...

). The full bars represent "on" bits in a pseudo-binary code in which the places represent, from left to right: 7, 4, 2, 1, 0. (Though in this scheme, zero

0 (number)

0 is both a numberand the numerical digit used to represent that number in numerals.It fulfills a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures. As a digit, 0 is used as a placeholder in place value systems...

is encoded as 11 decimal, or "binary" 11000.)

Example

The zip+4 of 55555-1237 yields a check digit of 2 for encoded data of 5555512372

Together with the initial and terminal frame bars, this would be represented as:

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

Delivery point

code. 62 bars total. This is usually referred to as the DPBC, or Delivery Point Bar Code. This is the predominant barcode in use currently , and it enables the Postal Service to sort mail into delivery point (address) sequence.

Discontinuation

POSTNET is being retired, and is being replaced by the Intelligent Mail barcode

Intelligent Mail Barcode

The Intelligent Mail Barcode is a 65-bar code for use on mail in the United States. The term “Intelligent Mail” refers to services offered by the United States Postal Service for domestic mail delivery. is intended to provide greater information and functionality than its predecessors POSTNET and...

(also known as OneCode Solution) which combines all previous Postal Service barcodes and marking into a single barcode. The Intelligent Mail Barcode was originally supposed to be required beginning May 2011 however the USPS postponed the requirement date, allowing mailers to continue receiving automation discount rates using the Postnet Barcode after the May 2011 deadline.

Checkdigit algorithm

The check digit is 10 minus (the digit-sum mod 10). That is, the check digit is calculated by:

Add up the digits, including the delivery point code if it is being used. If you are sending a letter to somewhere in Young America, Minnesota
Young America Township, Minnesota
Young America Township is a township in Carver County, Minnesota, United States. The population was 838 as of the 2000 census. Due to the presence of a major rebate-processing center, Young America Corporation, the town has more than 20 ZIP codes, including the ZIP code 55555...

, you might be sending to 55555-1237, which would have the sum of 38.
Find the remainder of this number when it is divided by 10, in this case 8. This could also be called the sum
SUM
SUM can refer to:* The State University of Management* Soccer United Marketing* Society for the Establishment of Useful Manufactures* StartUp-Manager* Software User’s Manual,as from DOD-STD-2 167A, and MIL-STD-498...

modulo
Modulo operation
In computing, the modulo operation finds the remainder of division of one number by another.Given two positive numbers, and , a modulo n can be thought of as the remainder, on division of a by n...

10. (Note that when summing the digits, any leading 1 in the 10's column of the current sum may be discarded.)
Subtract the sum modulo 10 from 10. Continuing with the example, 10 - 8 = 2. The check digit is therefore 2.

If calculated correctly, the sum of the ZIP, ZIP+4, or ZIP+4+delivery point digits and the check digit, modulo 10, will always be zero. Continuing with the example above, (5+5+5+5+5+1+2+3+7+2) mod 10 = 0.

Note that the Delivery Point

Delivery point

is often added after the ZIP+4 and before the check digit, in which case the computation of the check digit includes the ZIP+4 and the Delivery Point.

Example

Barcode formats

Discontinuation

Checkdigit algorithm

See also