An item can be one of three different levels:
- Base unit – the lowest level in an item hierarchy. A base unit is always contained in another item at case or pallet level, but itself contains no items identified with a GTIN.
- Case – the middle level in an item hierarchy. An item at case level contains other items and is itself contained in an item. An item at case level can contain items at base unit level or other items at case level.
- Pallet – the top level of an item hierarchy. An item at pallet level contains other items but is not itself contained in another item.
For each item at pallet and case level, the items contained at the next-lower level in the item hierarchy must be stated.
Example: There are 24 cases on a pallet. Each case contains six bottles of shampoo. The pallet is pallet level, the case of shampoo bottles is at case level and one shampoo bottle is at base unit level.
| Item level | Item | Contained item | Number of contained items |
|---|
Pallet | Pallet with cases | Case of shampoo bottles | 24 |
| Case | Case of shampoo bottles | Shampoo bottle | 6 |
| Base | Shampoo bottle | – | – |