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Plessey Code

Plessey Code (sometimes called UK Plessey Code) is a continuous, variable-length symbology that has been used to encode hexadecimal data. It was developed in 1971 by the Plessey Company of England and has produced several variations, including Anker Plessey and MSI Plessey.

It has a higher density than other common symbologies such as Code 39 - Regular or Interleaved 2 of 5 and has been most commonly used with dot matrix printers.

Although Plessey Code was originally developed for use in the library industry, its use in libraries is now quite rare. Plessey Code does not encode numbers efficiently, and other characteristics of the language make it one of the most error-prone of all barcode languages.

Symbol Structure

The symbol comprises the following elements:

Leading quiet zone
Forward start code of 1101, which indicates the beginning of the barcode
Encoded data
Checksum code
Terminating bar
Reverse start code of 0011, which, when combined with the forward start code, is used to detect the scan direction (left-to-right or right-to-left)
Trailing quiet zone

Each digit in a Plessey Code symbol is encoded in four bars (or bits). A wide bar followed by a narrow space represents a "1" bit, and a narrow bar followed by a wide space represents a "0" bit.

Plessey Code requires a quiet zone that is at least 0.125 inches wide on either side.

Character Set

Checksum

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