Code 39
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Code 39 can encode uppercase letters (A through Z), digits (0 through 9) and a handful of special characters like the $ sign. The barcode itself does not contain a check digit (in contrast to—for instance—Code 128), but it can be considered self-checking by some, on the grounds that a single erroneously interpreted bar cannot generate another valid character. Possibly the most serious drawback of Code 39 is its low data density: It requires more space to encode data in Code 39 than, for example, in Code 128. This means that very small goods cannot be labeled with a Code 39 based barcode. However, Code 39 is still widely used and can be decoded with virtually any barcode reader.
Code 39 gets its name because there are 9 light and dark bars in each code, and 3 of these bars are wide. 3 "wide" of 9 "bars".
The * character presented below is not a true encodable character, but is the start and stop 'symbol' for Code 39. The asymmetry of the symbol allows the reader to determine the direction of the barcode being scanned. This code is traditionally mapped to the * character in barcode fonts and will often appear with the human-readable representation alongside the barcode.
These tables outline the 3 of 9 specification:
| Legend | ||
| Format1 | Format2 | Desc |
| W | B | Wide - Black |
| N | b | Narrow - Black |
| w | W | Wide - White |
| n | w | Narrow - White |
| Code Details | ||
| Char | Format1 | Format2 |
| * | NwNnWnWnN | bWbwBwBwb |
| - | NwNnNnWnW | bWbwbwBwB |
| $ | NwNwNwNnN | bWbWbWbwb |
| % | NnNwNwNwN | bwbWbWbWb |
| (space) | NwWnNnWnN | bWBwbwBwb |
| . | WwNnNnWnN | BWbwbwBwb |
| / | NwNwNnNwN | bWbWbwbWb |
| + | NwNnNwNwN | bWbwbWbWb |
| 0 | NnNwWnWnN | bwbWBwBwb |
| 1 | WnNwNnNnW | BwbWbwbwB |
| 2 | NnWwNnNnW | bwBWbwbwB |
| 3 | WnWwNnNnN | BwBWbwbwb |
| 4 | NnNwWnNnW | bwbWBwbwB |
| 5 | WnNwWnNnN | BwbWBwbwb |
| 6 | NnWwWnNnN | bwBWBwbwb |
| 7 | NnNwNnWnW | bwbWbwBwB |
| 8 | WnNwNnWnN | BwbWbwBwb |
| 9 | NnWwNnWnN | bwBWbwBwb |
| A | WnNnNwNnW | BwbwbWbwB |
| B | NnWnNwNnW | bwBwbWbwB |
| C | WnWnNwNnN | BwBwbWbwb |
| D | NnNnWwNnW | bwbwBWbwB |
| E | WnNnWwNnN | BwbwBWbwb |
| F | NnWnWwNnN | bwBwBWbwb |
| G | NnNnNwWnW | bwbwbWBwB |
| H | WnNnNwWnN | BwbwbWBwb |
| I | NnWnNwWnN | bwBwbWBwb |
| J | NnNnWwWnN | bwbwBWBwb |
| K | WnNnNnNwW | BwbwbwbWB |
| L | NnWnNnNwW | bwBwbwbWB |
| M | WnWnNnNwN | BwBwbwbWb |
| N | NnNnWnNwW | bwbwBwbWB |
| O | WnNnWnNwN | BwbwBwbWb |
| P | NnWnWnNwN | bwBwBwbWb |
| Q | NnNnNnWwW | bwbwbwBWB |
| R | WnNnNnWwN | BwbwbwBWb |
| S | NnWnNnWwN | bwBwbwBWb |
| T | NnNnWnWwN | bwbwBwBWb |
| U | WwNnNnNnW | BWbwbwbwB |
| V | NwWnNnNnW | bWBwbwbwB |
| W | WwWnNnNnN | BWBwbwbwb |
| X | NwNnWnNnW | bWbwBwbwB |
| Y | WwNnWnNnN | BWbwBwbwb |
| Z | NwWnWnNnN | bWBwBwbwb |
External links
- The Barcode FAQ — links to barcode related white papers.
- Free font and encoder.
- http://www.barcodesinc.com/generator/
- Another free font and encoder.
- Code 39 spec at BARCODE Island.
- Code 39 spec at Barcode Man.
- Code 39 FAQ & Tutorial at ID Automation.
- Code 39 MIL-STD & ANSI specs at Barcode Products.
- Online Code 39 Generator