How do I identify an item from a barcode?

A barcode symbol is a machine readable image which conveys data. Barcodes can be divided into three general types: linear, stacked linear, and two-dimensional (or 2D): Linear Barcodes

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UPC-A

The UPC-A (also referred to simply as the UPC) is the standard retail “price code” barcode in the United States. To order UPC barcodes, please visit www.barcode-us.com.

UPC-A is strictly numeric; the bars can only represent the digits from 0 to 9. A UPC-A barcode contains 12 digits, along with a quiet (blank) zone on either side, and start, middle, and stop symbols. The middle symbol separates the left side and the right side, which are coded differently. When a digit is used on the left side, the bars are black and the spaces are white, and when it is used on the right side, the colors are reversed. The logic behind doing this is a little complicated, and involves a mathematical property called “parity,” but the effect is to reverse black and white, and to allow the scanner to tell whether it’s reading the code from left to right or from right to left.

The actual system of numbering depends on the type of product and the purpose of the barcode; the first digit of the barcode indicates the numbering system. The 10 digits that follow contain information about the product, and in all of the applications described below, the digit on the far right (not included in the application description) is a checksum, which can be used to test the accuracy of the scanner reading.

Below is a list of common UPC-A applications:

Typical retail products: Indicated by a first digit of 0, 1, 6, 7, or 8. The five remaining digits on the left side of the barcode are the identify the manufacturer. The five digits on the right are the product code (determined by the manufacturer).

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Pharmaceuticals: For drugs and some other pharmaceutical products. The 10 digits that follow form the NDC (National Drug Code) number, which identifies the manufacturer (or distributor or packager), the product (along with information such as dose, strength, and formula), and the size and other characteristics of the package.

Weight-based pricing: When products such as produce and meat are packaged and sold by weight, the UPC label begins with the number system code 2. The five digits that follow it on the left identify the item, and the ones that follow are for the product weight or the price.

barcode-2

Coupons: The numbering system digits 5 and 9 are for coupons. As with retail products, the five left-hand digits are the manufacturer identification. The five digits on the right tell what products the coupon applies to and the discount.

Reserved: Number system 4 is reserved for use by individual retailers or wholesalers, and is often used for store coupons, customer loyalty cards, and similar items.

UPC-E

The UPC-E barcode can be used when available space is too small for a UPC-A barcode. it contains the same information as a UPC-A label, but it uses some tricks to reduce the number of digits to six.

he UPC-E code’s most basic trick is to remove trailing zeroes in the manufacturer’s code, and leading zeroes in the product code. The details of the technique are complicated, and it doesn’t work for everything, but it does cover all codes with a total of 5 leading/trailing zeroes, as well as a significant number of codes with four zeroes.

UPC-E uses a much more complex trick to compress the checksum and the number system code. A side-effect of this technique is that the only numbering system codes allowed are 0 and 1.

EAN-13

The EAN-13 code is basically an international version of UPC-A. EAN-13 adds a 13th digit on the far left side of the UPC-A code (so that it becomes the first digit). The EAN-13 standard includes UPC-A barcodes; adding a leading 0 to a UPC-A code turns it into the equivalent EAN-13 code.

The main differences between EAN-13 and UPC-A (besides the extra leading digit) are that with EAN-13, the manufacturer and product codes can vary in length, and that the first three digits make up the GS1 prefix, or “country code.”

The GS1 prefix is issued by GS1, the international barcode standards organization. It may identify the national GS1 member organization or a special use. The member organizations issue the manufacturer’s codes, and the manufacturers set their own product codes. The complete EAN-13 barcode number, consisting of the GS1 prefix, the manufacturer’s code, the product code, and the checksum digit, is also known as the GTIN, or Global Trade Item Number. Besides the national GS1 prefixes, typically used for standard retail items, there are prefixes for specialized purposes, such as coupons, refunds, serial publications (magazines and newspapers), books (ISBN), and sheet music (ISMN).

In the United States, price code scanners and point-of-sale/inventory systems are typically capable of reading both UPC-A and EAN-13 barcodes.

EAN-8

EAN-8 is a GS1 barcode for use on small items when a full EAN-13 barcode label would be too large to fit. It consists of eight digits — four on the left side and four on the right. They use the same kind of encoding as UPC-A and EAN-13, with the last digit being used as a checksum.

An EAN-8 barcode can be used either with GTIN-8 or RCN-8 product identification numbers.

GTIN-8 is like a shortened version of the EAN-13 code, but without information about the product’s origin. In order to use a GTIN-8 number, a manufacturer must request it from the national member organization. An EAN-8 barcode that encodes a GTIN-8 identification number is valid for global use, like an EAN-13 barcode.

RCN-8 numbers, on the other hand, are for use only on house-brand or store-label products, and can be used only within the business that issues it. If it is scanned by another retailer, it will give an incorrect reading.

Code 128

The UTF and EAN “price code” barcodes described above encode only numbers, but Code 128 is a linear barcode that encodes both letters of the alphabet and numbers, making it useful for a variety of purposes beyond basic pricing and inventory.

Code 128 encodes the 128-character ASCII set, which includes all of the alphabetic, numeric, punctuation, and arithmetic characters found on an English-language computer keyboard, plus several non-visible control characters.

In order to include all of the ASCII characters, Code 128 uses three different character sets:

The Code A set consists of capital letters, numbers, punctuation, and nonprinting control characters

Code B is similar to Code A, but replaces most of the control characters with the full set of lower-case letters, plus some added punctuation

Code C does not include any letters or punctuation; it is made up of number pairs, from 00 to 99. This saves space when encoding numbers.

A single Code 128 barcode can include characters from all three character sets, switching between them repeatedly.

The basic Code 128 barcode format consists of a start code (which sets the initial character set to A, B, or C), the code data, a checksum digit, and a stop code, which marks the end of the barcode. As with other linear barcodes, there are blank quiet zones on either side.

GS1-128 (also known as UCC-128 and EAN-128) is an international standard for using Code 128 in supply-chain barcode labels. GS1-128 consists of the basic Code 128 format with an Application Identifier added to the code data.

Application identifiers are 2 to 4 characters in length, and identify the type of data that will follow — typically, standard supply-chain applications, such as serial number, number of containers, lot number, weight, volume, etc., including tracing and transaction information. Each identifier sets the length and format of the data that follows it.

Because most application code data is fixed-length, it is possible to include several codes in one GS1-128 barcode, simply by adding new Application Identifiers and code data.

Code 39

The Code 39 symbology is also alphanumeric and variable-length. It was developed in 1974, and is still in relatively wide use; most barcode readers can read Code 39. In Code 39, each character is made up of five bars and four spaces, with three of those bars/spaces being wide, and the others narrow. As a result, all characters have the same width, and a Code 39 barcode generally takes up more space than the equivalent Code 128 barcode.

The basic Code 39 system is made up of 43 characters, including capital letters, numbers, and some special/punctuation characters. Depending on the application and the system, it may be possible to use all 128 ASCII characters.

A Code 39 barcode consists of a start character, the coded data, and a stop character. Both the start and stop characters are identical, and are generally represented by the * asterisk symbol. there is no checksum character, but some error-checking capabilities are built into the coding system.

Code 39 is used for many of the same types of applications as Code 128, and official Code 39 standards (including an ANSI standard) exist. It is not, however, included in the GS1 system.

Interleaved 2 of 5

Interleaved 2 of 5 (or ITF) is a variable-length numbers-only linear barcode. It encodes digits in pairs, with the first digit in each pair represented by bars, and the second digit represented by spaces, so that they are interleaved. Two of the five bars or spaces representing each digit are wide, and the others are narrow.

Interleaved 2 of 5 is included in the GS1 system as the ITF-14 standard, which has a set length of 14 digits.

An ITF barcode consists of a start code (two narrow bar/narrow space pairs), the encoded data, a checksum digit (required for ITF-14, optional elsewhere), and a stop code (wide bar, narrow space, narrow bar), with quiet zones on either side.

Patterns identical to the start and stop code can occur within the coded data, which can result in a bad reading if the scanner does not read the code all the way across. To prevent this, the ITF-14 standard requires a heavy black border called the bearer bar.

ITF barcodes are typically used in wholesale and shipping for box or carton lots of a product. A specialized version of the ITF barcode is also used on 135 film canisters.

Codabar

Codabar was originally developed by Pitney Bowes in 1972. It is a variable-length barcode that uses a small set of bars to encode the digits 0 through 9, and in some applications, a few symbols such as the dollar and plus signs. it also includes four start/stop symbols (generally represented by A, B, C, and D). A Codabar code consists of a start symbol, the coded data, and a stop symbol. it is self-checking, although some applications do specify a check digit.

Codabar has traditionally been used by libraries, by blood banks, and for airbills by some companies such as Federal Express, and is still in use for some of those applications.

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