The acronym NSN means NATO Stock Number, it’s a 13 digit number that identifies a unique Item of Supply, the last 9 number are called NIIN, NATO Item Identification Number, it is invariable and remains associated with the item of supply throughout its life cycle.

The NSN is divided into 3 parts:

• The first 4 digits are the NATO Supply Classification Code and relate the IoS to the group and class of similar Items of Supply.

• The next 2 digits indicate the NCB assigning the NSN.

•  The final 7 digits of a NSN are computer allocated and have no inherent significance other than to uniquely identify the IoS to which they are allocated.

With all those references, the NATO has a catalogue, The NATO Master Catalogue of References for Logistics, with descriptions and technical data, designed to achieve the maximum effectiveness in logistics support and to facilitate material data management. It is necessary to record manufacturers' names against codified Items. To meet this requirement, a 5 character NATO Commercial and Government Entity Code (NCAGE), is assigned to each manufacturer. Every part number listed on NSNs in the NCS is accompanied by a NATO Commercial and Governmental Entity (NCAGE) code. These five character codes identify exactly who the manufacturer or other organization is.

Military inventories are complex and comprehensive in their content. To enable efficient management of these complex inventories in the NCS the components of the inventory are split into a hierarchical structure of discrete Groups and Classes. Each Group is formed by Items of Supply of the same physical or performance characteristics or utilization in the same application, and is indicated by a 2 digit code (NATO Supply Group) NSG.

Within each Group, Items of Supply are further divided into Classes. These Classes are indicated by an additional 2 digit code forming, together with the Group code, a 4 digit NATO Supply Classification (NSC). The NATO Supply Classification System is uniform throughout all nations and each IoS concept identified using this System will be assigned a unique 4 digit Classification code.

The NSN is a uniform, adaptable, simple, stable, and compatible number, which actually records more than 10 million different Items of Supply