Bar coding - (American) Universal Product Code

The American Universal Product Code (UPC) was developed in 1970 to be succeeded by the European Article Number (EAN) in 1977.
The Uniform Code Council announced Monday, June 9, 1997 that UPC will be phased out by the year 2005, since the 12-digit UPC will run out of numbers by then. The United States will adopt EAN (what the rest of the world uses) which has thirteen digits.

Versions

csbarcu1.gif (1809 bytes)
csbarcue.gif (1336 bytes)

The Universal Product Code (UPC) specifications include three versions:
- UPC-A: the regular version, is used to encode a twelve digit number.
- UPC-E: A zero suppressed version, is a six digit code used for marking small packages.
  
  The middle narrow bars are not contained in UPC-E, and its right hand guard pattern has three bars instead of two.
- UPC-D: the variable length version, is used in limited special applications (not commonly for package marking).
With all symbols it makes no difference which direction the scanning beam traverses the barcode (left->right, or right->left)

Number system characteristics

Character	Usage
0	Regular UPC Codes
1	Reserved
2	Random weight items which are symbol marked at the store level
3	National Drug Code and National Health related Items Code
4	For use without code format restrictions and with check digit protection for in store marking of non food items.
5	For use on coupons
6,7	Regular UPC Codes
8,9	Reserved

UPC-A construction

csbarcu0.gif (3096 bytes)

The UPC-A symbol is physically constructed as follows:
- Left hand guard bars, encoded 101
- Number system character, encoded as a left hand character
- First five data characters, encoded as left hand characters
- Center guard pattern, encoded 01010
- Last five data characters, encoded as right hand characters
- Check character, encoded as a right hand character
- Right hand guard bars, encoded 101