In addition to ASCII characters, Code 128 also allows encoding of four special function codes (FNC1 - FNC4), which are listed in Table 3.1, “Encoding Code Table”.
The meaning of function code FNC1 and FNC4 were originally left open for application specific purposes.
Recently an agreement was made by the Automatic Identification Manufacturers Assoc. (AIM) and the European Article Numbering Assoc. (EAN) to reserve FNC1 for use in EAN applications.
FNC1 at the beginning of a bar code indicates that it begins with a 2- 3- or 4-digit application identifier assigned by the Uniform Code Council, which explains the following digits. For example, application identifier 421 indicates that an ISO 3166-1 numeric country code and ship-to postal code follows.
For example, the U.S. ZIP code for the White House would generally be printed as "(421) 840 20500", but would actually be coded as "[Start C] [FNC1] 42 18 40 20 50 [Code A] 0 [Check symbol 80] [Stop]"
|The FNC1 for the UCC/EAN-128|
The function 1 (FNC 1), which follows the start character, enables scanners and processing software to auto-discriminate between UCC/EAN-128 and other barcode symbologies, and subsequently only process relevant data.
FNC2 is used to instruct a bar code reader to concatenate the message in a bar code symbol with the message in the next symbol.
FNC3 is used to instruct a bar code reader to perform a reset. When FNC3 is encoded anywhere in a symbol, any data also contained in the symbol is discarded.