The DX number is assigned by the International Imaging Industry Association

International Imaging Industry Association

The International Imaging Industry Association was created by a merger of the PIMA and the Digital Imaging Group in 2001. It is a common forum for the industrial imaging industry....

 (I3A). It uniquely identifies the type and manufacturer (sensitizer) of a film emulsion. A proprietary list of DX numbers for APS

Advanced Photo System

Advanced Photo System is a film format for still photography first produced in 1996. It was marketed by Eastman Kodak under the brand name Advantix, by FujiFilm under the name Nexia, by AgfaPhoto under the name Futura and by Konica as Centuria.- Design :The film is 24 mm wide, and has three...

 and 135 film

135 film

The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...

 is prepared yearly or as needed. (DX Codes for 135-Size Film, 2004, I3A). The list is available for sale from the I3A.

DX number composition

A DX number has two parts separated by a dash: the "combination code" also known as "DX Number Part 1 " followed by a "specifier number", or "DX Number Part 2". For example, Agfa Perutz 3-color 200 ISO film is assigned 115-4 (I3A).

DX barcode

For 135 film cartridges the DX number is hashed

Hash function

A hash function is any algorithm or subroutine that maps large data sets to smaller data sets, called keys. For example, a single integer can serve as an index to an array...

 to produce a four digit code. A suffix digit for the number of exposures and a manufacturer's proprietary prefix digit are concatenated to form a 6 digit decimal code. The code is printed in human-readable

Human-readable

A human-readable medium or human-readable format is a representation of data or information that can be naturally read by humans.In computing, human-readable data is often encoded as ASCII or Unicode text, rather than presented in a binary representation...

 text and also represented as an Interleaved 2 of 5

Interleaved 2 of 5

Interleaved 2 of 5 is a continuous two-width barcode symbology encoding digits. It is used commercially on 135 film and on cartons of some products, while the products inside are labeled with UPC or EAN....

 barcode

Barcode

A barcode is an optical machine-readable representation of data, which shows data about the object to which it attaches. Originally barcodes represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or 1 dimensional . Later they evolved into rectangles,...

. Size and position conform to the ANSI

American National Standards Institute

The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...

/NAPM IT1.14:1994 standard.

To generate digits 2 through 5, the combination code is multiplied by 16 and added to the specifier number. The result is prefixed with zeroes to make 4 digits. For the Agfa film 115-4 above, the digits would be 1844 (16 × 115 + 4).

Digit 1 is any digit from 0 to 9 and is assigned by the manufacturer.

Digit 6 is a code digit for the number of full-frame exposures: 1 is for 12 exposures, 2 for 20 exposures, 3 for 24, 4 for 36, 5 for 48, 6 for 60, 0 for 72 and 7 for non-standard lengths such as 24+3.

The barcode is located between the electrically-read silver and black DX Camera Auto-Sensing Code and the film cartridge exit lip.

The barcode is optically scanned by many film-processing machines when the cartridge is inserted for developing. (Kodak patent 5761558)