Code 39 - Regular

Code 39 - Regular

The Code 39 - Regular symbology was developed to meet the need for a fully alphanumeric barcode for use with data-entry systems. (An alphanumeric symbology can represent both letters and numbers in its barcode.) It is currently the most widely used alphanumeric barcode and has been accepted as a standard code by many organizations and given different names, including the following.

  • AIAG: Automotive Industry Action Group.
  • LOGMARS: The Logistics Applications of Automated Marking & Reading Symbols (Department of Defense), recommends the use of Code 39 - Regular as the standard DOD barcode symbology. MIL-STD-1189 defines Code 39 - Regular as the standard symbology for marking unit packs, outer containers, and selected documents.
  • HIBC: Health Industry Barcode Council.

In addition, the following organizations also use Code 39 - Regular:

  • ANSI: American National Standards Institute. Code 39 - Regular is the only alphanumeric barcode described in their 1981 specifications draft titled "Specifications for barcode Symbols on Transport Packages & Unit Loads.
  • DSSG: Distribution Symbol Study Group.

The Character Set

Code 39 - Regular contains the following 43 usable characters:

  • The ten digits 0 - 9.
  • The 26 capital letters A - Z.
  • The six symbols % + $ / . -
  • The space character.

In addition to these 43 characters, Code 39 - Full ASCII lets you represent all characters of the 128-character ASCII character set.

The Density

Code 39 - Regular has a moderate character density. The densest Code 39 - Regular barcode that can be printed on an Epson-compatible dot-matrix printer is about 5.5 cpi (characters per inch). However, because not all dot-matrix printers produce good codes at this density, we suggest not going above 5 cpi unless you have a 24-pin printer. On laser printers, the maximum suggested character density for a Code 39 - Regular barcode is 9.4 cpi. (For reading barcodes of this density, we recommend use of a high resolution optical scanner.)

Barcode messages that only contain numbers can be encoded in the Interleaved 2-of-5 symbology using about half the space required by Code 39 - Regular.

The Symbology Structure

Each Code 39 - Regular character is represented by nine elements: five bars and four spaces. The name "Code 39 - Regular" comes from the fact that, of the nine elements in each Code 39 - Regular character, three of the elements are always wide and six are narrow.

A fifth space, an "intercharacter space", separates each barcode character from the next, but is not actually itself a part of a barcode character. The width of this space is not critical and is set to be identical to the width of a narrow space.

The Start and Stop Characters

Code 39 - Regular also has a "start/stop" character. This character is used at both the beginning and the end of the barcode message to signal a barcode reader that a Code 39 - Regular barcode has been scanned. This character is commonly designated as an asterisk (*), but you may choose to have no start/stop characters at all or choose to let the data source specify the start or the stop character, or both. The start and stop characters are not transmitted as part of the barcode, and is not included in any check digit calculations.

More barcode symbologies

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