The regular Code 39 barcode symbology supports only 43 characters. If you wish to encode other ASCII characters then 'Extended Code 39' (also known as Code 39 Full ASCII) must be used. Extended Code 39 obtains the additional characters by combining two regular Code 39 characters. The barcode decoder interprets the character pair as a single ASCII character.

Applications
Code 39 Full ASCII is used in manufacturing, military, and health applications.

Benefits
The extended 3 of 9 code is a general purpose code which can code any ASCII character unlike Code 39, that encodes only 43 characters.

Limitations
Extended Code 39 takes twice as much space as Code 39 as it uses two 3 of 9 code characters for each of the 128 ASCII characters. Not suitable for small products.

Technical Specifications
Extended code 39 retains all of the encoding specification of Code 39. The full 128 character ASCII character set can be encoded with the Code 39 barcode using combinations of two symbol characters made up of one of the four Code 39 characters '+', '$', '%', and '/', which act as a shift charcter, followed by one of the 26 Code 39 barcode alphabets.

Additional Information
It is recommended to use Code 128 or PDF417 if large amount of data needs to be encoded, as extended version of Code 39 is very inefficient.

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