Code 39 is an alpha-numeric code. This symbology includes 43 characters :A-Z, 0-9, and characters for a dash (-), period (.), dollar sign ($), slash (/),plus sign (+), percent (%), and a space. Each character in Code 39 is made up of five bars and four spaces. Of these nine bars and spaces, six are always narrow and three are always wide. There is also a start and stop character to initiate and to stop the reading. The bar code shown is a typical Code 39.

LOGMARS  (with OCR-A characters)

       Code 39 is a bi-directional bar code. This means that a stop can be read first and the number read backwards, and it can still be recognized in its proper sequence.

       In 1977, the U.S. Department of Defense created the Logistic Application of Automated Marking and Reading Symbols (LOGMARS) Study. In 1981,the LOGMARS Study chose Code 39 as the choice for alpha-numeric marking and required that the code appear on government shipments and containers. Another reason that Code 39 is popular in forms usage is that it is able to be printed with a numbering head.  (more detail about Code 39)