Start and Stop Pattern
Start and stop patterns are unique marker characters at each end of a linear barcode that tell the scanner the symbology in use, where data begins, and the reading direction.
What You Need to Know
Every linear symbology reserves distinctive bit patterns that can never occur in ordinary data. Code 128's 13-module stop pattern, Code 39's asterisk-delimited framing, and Codabar's A/B/C/D start-stop letters all serve the same purpose: they let a decoder synchronize on the symbol, identify the code set, and know when the data ends — including detecting reverse-direction scans, since the stop pattern of a backwards symbol reads as a start.
This is why quiet zones flank these markers rather than the data itself: a scanner sweeping into the label needs the clean transition directly before the start pattern to measure the first element width accurately. Start and stop characters are added by the encoder and are invisible in the transmitted data (Code 39's asterisks are the familiar exception — printed but not transmitted by most scanners).
Where Start and Stop Pattern Applies
A high-density, variable-length linear barcode that encodes all 128 ASCII characters, and the backbone symbology of modern logistics.
Generate Code 128 →The classic self-checking alphanumeric barcode: 43 characters, simple structure, still everywhere in industry.
Generate Code 39 →A self-checking numeric barcode with start/stop letters, historically used by libraries and blood banks.
Generate Codabar →The 13-digit retail point-of-sale barcode used on consumer products worldwide outside North America.
Generate EAN-13 →A dense digits-only linear barcode that interleaves bar and space character pairs — logistics workhorse for numeric data.
Generate ITF (Interleaved 2 of 5) →