Standard 2 of 5 was invented in early 1960s. Since then it has been widely used in warehouse, photo finishing and airline industries. It is also called industry 2 of 5.
Standard 2 of 5 is a numeric symbology and its character set includes 10 digital characters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
The symbology receives this name because every character is encoded with 5 bars where 2 bars are wide. Code25 only uses bar width to encode the data. Interleaved 2 of 5, however, uses both widths of bars and spaces.
A complete Standard 2 of 5 barcode must include a start character and a stop character. Optionally it ends with a modulo 10 check digit.
Standard 2 of 5 is a very simple and low density symbology. Its variant, Interleaved 2 of 5 (ITF25), has a slightly higher density.
Industry 2 of 5 – Identical to Standard 2 of 5.
Standard 2 of 5 Mod 10 – A modulo 10 check digit is appended to the barcode message to perform checking.
A typical Code25 barcode has the following structure:
A start character
Message encoded
Optional Mod 10 check digit
A stop character
Start with the right-most digit in the message; mark the character with even and odd position. The right-most digit has the even position.
Sum all digits in the odd position.
Sum all digits in the even position, and then multiply by 3.
Add the result 2 and result 3.
Divide the result of step 4 by 10, the check digit is the result equal to that 10 minus the remainder. In the case the the remainder is 0, the check digit is 0.