Universal Product Code (UPC) was initially developed in the 1970s for use by the US grocery industry, and its use has spread into other retail marketplaces in the US and internationally.
UPC-E is the compressed version of UPC. It suppresses zeroes to save space and was developed for items that are too small to accommodate the larger UPC-A barcode.
UPC-E is defined in ISO/IEC 15420 Information technology - Automatic identification and data capture techniques - EAN/UPC bar code symbology specification. The GS1 implementation is defined in GS1 General Specifications.
The symbol comprises the following elements:
Leading quiet zone
Guard pattern (start character)
Six symbol characters
Guard pattern (stop character)
Trailing quiet zone
UPC-E encodes six digits of numeric message data together with a number system digit and a check digit, for a total of eight digits.
Most barcode symbologies print bars and spaces in only two widths, but with UPC, four different widths are used. This enables each numeric character to be represented by using just two bars and two spaces, which is the fewest number of modules required per character of any symbology.
Although UPC barcodes come in a number of different message lengths, these lengths are not fully variable as they are with other barcode symbologies. UPC-E uses seven digits, one of which is a check digit.
Guard bars. The guard bars are the start and stop characters in a UPC-E symbol.
The start character is made up of three modules as follows:
The stop character is made up of six modules as follows:
The bars for these characters are longer than the bars that encode data, and they are sometimes referred to as security bars.
This symbology supports all numeric digits (0-9).
UPC-E contains a check digit that is based on the modulo 10 (mod 10) algorithm.
With four available printing widths for the bars and spaces instead of just two, UPC-E takes about half the number of bars and spaces relative to Interleaved 2 of 5 to represent each character. However, the use of the wider bars and spaces nullifies this space savings. Interleaved 2 of 5 codes pack data more densely than UPC-E does.
Two-digit and five-digit add-on symbols (supplemental barcodes) are available for adding to the right of the UPC-E symbol. These add-on symbols are usually used to add a date or a manufacturer's suggested retail price (MSRP) to periodicals, books, and weighed products, such as food. The character set and density of the add-on symbols are the same as those of UPC-E. A human readable interpretation is always included.
The start characters for the two-digit and five-digit add-on symbols are made up of three modules as follows:
The add-on symbols do not use a stop character or center character.
Because many purchased goods are conveniently prelabeled with UPC barcodes, you will want a barcode reader that can read these symbologies. These barcodes are usually produced photographically or with a laser printer. However, since most barcode readers can automatically discriminate between the various barcode symbologies, it is very easy to combine different barcode symbologies in a given application environment.
If you have a barcode reader that has automatic discrimination, we recommend using either Interleaved 2 of 5 or Code 39 for your in-house printed barcodes. Because UPC is a numeric-only code, Interleaved 2 of 5 would be the preferred substitute, because it uses about half the space that Code 39 uses.
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