GS1 Application Identifiers (AI) are used to enable scanners to understand what information it is reading. An AI code is required in front of each piece of data.
Each AI is a numeric code made up of two, three, or four digits.
Common AIs include:
01 Global Trade Item Number (GTIN)
391 Sell price
310 NET weight in kgs
17 Use by/ Expiry date
15 Best before date
10 Batch/Lot number