The GS1 standard identifiers for products, locations, assets and pallets are the basis of the GS1 System. They provide the unique identification that can be shown in a bar code, carried in an RFID tag or communicated electronically. However sometimes more information needs to be shown in the bar code. The GS1 standards for Application Identifiers provide this ability.

The Application Identifier standard defines a series of types of data that can supplement the identity numbers. They include:

• Batch number
• Serial number
• Best before date
• Expiry date
• Weight

Each defined data type has its own prefix (which is the “Application Identifier” that gives this standard its name) to distinguish it from all the others. When the identification numbers are supplemented by more information in this way, only GS1-128, DataBar or datamatrix barcodes can be used for bar coding.