List of NATO Supply Classification Groups

The NATO Item Identification Number or National Item Identification Number (NIIN) is a 9-digit alphanumeric code created by the NATO Codification Bureaux to designate unique items of supply. The NATO Stock Number or National Stock Number (NSN) is a 13-digit alphanumeric code consisting of a Group of Supply, a Class of Supply and the unique NIIN to designate unique items of supply grouped by their relative catalog category.

Source: Wikipedia — List of NATO Supply Classification Groups (CC BY-SA 4.0)