Linear Symbologies

A linear or one-dimensional (1-D) symbology is a single row of bar and space elements. These elements can vary by width (as with UPC-A) or by height (as with Royal Mail 4-State Customer Barcode).

Some linear symbologies use interleaving. In interleaving, the first data character is encoded by using black bars of varying width. The second data character is then encoded by varying the width of the white spaces between these bars. In this way, characters are encoded in pairs in the same section of the barcode, which saves space.