Code 2 of 5 is interesting because of its similarity in design to Postnet. Both are 2 of 5 codes, but Code 2 of 5 encodes using bar width instead of bar height. Code 2 of 5 has been in use since the late 1960's for airline tickets, photo developing envelopes, and warehouse sorting systems (see The Bar Code book section 4.3.8).

Code 2 of 5 only encodes data in the bars and there are only 2 bar widths. As such, it is a fairly inefficient code in terms of how much space is required to encode a single digit. Each bar is followed by a space of a size that is uniform throughout the code, typically the same width as the narrow bar. Each code begins with a START pattern and ends with a STOP pattern.

Here is the character pattern table. Wide & Narrow bars are denoted with W & N respectively.

0: NNWWN
1: WNNNW
2: NWNNW
3: WWNNN
4: NNWNW
5: WNWNN
6: NWWNN
7: NNNWW
8: WNNWN
9: NWNWN
START: WWN
STOP: WNW


Codabar	Code 2 of 5	Code 3 of 9	Interleaved 2 of 5
Postnet	UPC	Code 128	Code 16k

Thu Jul 24 11:01:25 PDT 2008		barcode/code25.src
Updated: Thu Aug 18 2005 9:31.35		Viewed: never