Code 128 is a variable length,high density, alphanumeric symbology. Code 128 has 106 different bar and space patternsand each patterncan have one of three different meanings,depending on which of three differentcharacter sets is employed. Specialstart characters tell the reader which of the charactersets is initially being used and three special shift codes permitchanging character sets inside a symbol. One character sets encodes all upper case and ASCII control characters, another encodes all upper and lower case characters and the third set encodes numeric digit pairs 00 through 99. This third characterset effectively doubles the code density when printing numeric data. Code 128 also employs a check digit for data security. In additionto ASCII characters, Code 128 also allows encoding of four specialfunction codes (FNC1 - FNC4). The meaning of function code FNC1 and FNC4 were originally left open for application specific purposes. Recently an agreement was made by the AutomaticIdentification Manufacturers Assoc.(AIM) and the European Article NumberingAssoc. (EAN) to reserveFNC1 for use in EAN applications. FNC4 remainsavailable for use in closed system applications. FNC2 is used to instruct a bar code reader to concatenate the message in a bar code symbol with the messagein the next symbol.FNC3 is used to instructa bar code reader to perform a reset. When FNC3 is encoded anywherein a symbol, any data also contained in the symbolis discarded.
NOTE: All TALtech bar code softwareproducts will automatically select the proper character sets and insertthe necessary start character and shift codes so that the resulting bar code will be as short as possible. The check digit will also be calculated automatically.