Quick answer
Code 128 is a high-density linear barcode that can encode the full ASCII character set through three character subsets. The symbol includes a start code, data values, a weighted checksum, a stop pattern, and quiet zones. Subset C compresses pairs of digits, which is why numeric shipping identifiers can be compact.
How to do it
- Enter the identifier exactly as the receiving system expects it.
- Let the encoder select efficient character subsets and calculate the checksum.
- Export at sufficient width and test with the actual scanner workflow.
Sets A, B, and C
Set A includes uppercase characters and controls, Set B covers upper- and lowercase characters, and Set C encodes numeric pairs. An encoder can switch sets inside one symbol. Users usually should not insert these control choices manually unless following a formal specification.
Code 128 versus GS1-128
GS1-128 uses the Code 128 symbology but adds a function character and standardized application identifiers for fields such as GTIN, batch, and expiry. A generic Code 128 image is not automatically a compliant GS1-128 label.
Common mistakes to avoid
- Removing required leading zeros.
- Printing below the scanner's minimum bar width.
- Calling a generic Code 128 symbol GS1-128.
Try the related tool
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