Code 39 is also known like ” USS Code 39″ , ” Code 3/9″ , ” Code 3 of 9″ , ” USD-3″ , ” Alpha39″ , ” Type 39″ , ” Code 93″. It is the 9 symbolism of bar code that can codify the letters in capital letter from a to z, numbers from 0 to and a handful of special characters as the sign $ . The bar code in himself does not contain a control digit, in resistance for example as it happens to Code 128, but can be considered of automatic control by some, on the base of which a bar interpreted erroneously single cannot generate another character valid. Possibly, the most serious disadvantage of Code 39 is its low densidad of data, since more space is required to codify data in the code 39 that, for example, in code 128. This means that the very small products cannot be labellings with a bar code Code 39 as bases. Nevertheless, Code 39 is still widely used and can be decoded with almost any reader of bar code. An advantage of Code 39 is that since there is no necessity to generate a control digit, it can easily be integrated in the system of existing impression adding to a source of bar code to the system or the printer and soon to print the raw data in that source.

Code 39 (also known as 3 9 of bar code) is a variable, discreet length, alphanumeric bar code. Its set of characters contains 43 significant characters: 0 – 9, AZ, -. , $,/, +, %, and space. Each character is made up of nine elements: five I sweep and four spaces. Three of the nine elements are wide (binary value 1), and six elements are narrow (binary value 0). Nevertheless, the additional common character (*) is used to initiate and to stop delimiters. The name code 39 derives the fact that three of the nine elements that constitute a word in key they are width elements and the six rest are narrow. Code 39 was developed by the Dr. David Allais and Ray Stevens de Intermec in 1974. Later it was standardized like ANSI MH 10.8 M-1983 and MIL-STD-1189.