It should be noted that Code 128 (ISO / IEC 15417) is a neutral barcode that can contain various data. Simply put, it's the disk. The data structure that is encoded follows ISO / IEC 15418 and Chapter 3 of the GS1 General Specifications. However, the use of the GS1 data structure never changes the properties of Code 128, which are specified in ISO / IEC 15417. That the GS1 data structure is not tied to the code type can be seen in the applications in the DataMatrix code , QR code and GS1 Databar . To put it correctly, GS1-128 is the following: A Code 128 that records data structured according to the GS1 specifications.
In practice, the apparently different code type GS1-128 very often leads to confusion, confusion and errors. If the background is known, the designation GS1-128 is a very concise form that expresses the connection between the data carrier and the data structure.
The coding of the special character FNC1 after the start character is mandatory. This shows the applications that the code content is structured according to GS1 specifications. The basis of this concept is laid down in international standards. GS1 is registered as an issuing agency according to ISO / IEC 15459-2. ISO / IEC 15434 specifies how the structure used can be recognized and ISO / IEC 15418 describes the data structure.
So that the data obtained from a GS1-128 barcode symbol can be clearly interpreted, the format and meaning of each individual data content that can be represented in the GS1 data identifier concept is described precisely.
Each data element contains a two- to four-digit data identifier, which must be placed in front of the information to be encoded and which makes it distinguishable from other data. These identifiers enable the recipient of the bar-coded information to interpret all data read. Based on his own requirements, he can select which information should be processed further in the downstream application programs and which should be ignored. Each identifier is assigned a unique format, with both fixed and variable lengths of the identifier. Identifiers of variable length either use the maximum length assigned to them or are limited by a control character “FNC1”. In this way, an application can determine the end of an identifier and thus the beginning of the subsequent identifier.
The standard not only defines a uniform syntax, but also a uniform semantics of bar-coded information through the use of data identifiers ( application identifiers ). With the data identifier, the meaning and format of the subsequent data field are known to everyone involved in the process chain; A mix-up between the consignment number and an article label that happens to be attached to the package is impossible, even if they use the same syntax, the code alphabet of Code128 . By using a "symbology identifier", the control character "FNC1", each GS1-128 application can be clearly distinguished from Code 128 applications.
Frequently used data identifiers are, for example:
- 00 Number of the shipping unit : a worldwide unique number of the delivery, international: SSCC (Serial Shipping Container Code)
- 01 GTIN of the trade item (article number, 14 digits)
- 10 Lot number / batch number of the item
- 15 best before date (YYMMDD)
- 17 Expiry Date (YYMMDD)
- 21 serial number
- 30 quantity, variable length
- 310x net weight in kilograms (6-digit integer value with leading zeros), a value for x indicates the number of decimal places
Core elements of the GS1-128 data standard
- Exact definition of data elements
- Assignment of qualifying data identifiers
- Definition of formats
- embedded in protected data carriers
The data in Code 128 are not protected if they are encoded according to the GS1 structure specification. The identification character FNC1 as the first character in the code is reserved so that the GS1 data structure can be reliably recognized. However, it is always possible to encode the FNC1 character first and then encode proprietary data behind it. Although this approach is not very recommendable, there is no way to forbid it (ISO and DIN standards have no legal force unless a law refers to a standard). The statement “protected data carrier” is therefore a pure instrument for advertising the use of GS1 solutions.