Introduction

Standard 2 of 5 is a very simple symbology in that all encoding information is encoded in the width of the bars. The spaces in the barcode exist only to separate the bars themselves. Additionally, a bar may either be wide or narrow, a wide bar generally being 3 times as wide as a narrow bar. The exact size of the spaces is not critical, but is generally the same width as a narrow bar.
The symbology receives this name because every character is encoded with 5 bars where 2 bars are wide. Standard 2 of 5 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.
Standard 2 of 5 also is known as Code25.
Variants
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.
Structure of Standard 2 of 5
A typical Standard 2 of 5 barcode has the following structure:
1. A start character
2. Message encoded
3. Optional Mod 10 check digit
4. A stop character
Check Digit Calculation
1. 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.
2. Sum all digits in the odd position
3. Sum all digits in the even position, and then multiply by 3
4. Add the result 2 and result 3;
5. Divide the result of step 4 by 10, the check digit is the result equal to that 10 minus the remainder
Industrial 2 of 5
"Industrial 2 of 5" is another name of "Standard
2 of 5", and is functionally identical to the Standard
2 of 5.