Also known as the National Stock Number (NSN), NATO Stock Number is a 13 digit numeric code recognized in the US. This purpose of this is to identify all the ‘standard material items of supply’ as they are acknowledged by all the NATO countries which include the United States Department of Defense.Following the NATO Standardization Agreements, the NSN is recognized in all the countries that are part of the treaty and they all accept it as NATO Stock Number too.  It is also important to note here that many of the countries that make use of the NSN program are not even members of the NATO such as japan, Australia and New Zealand.In this regard, a two digit Material Management Aggregation Code (MMAC) suffix is attached which symbolizes the purpose of the stock number but it is not taken to be the part of the NSN. Any item which has an NSN is termed as ‘stock-listed’.Classification of NSN
In the beginning, each element from a to m was initially intended to be a single decimal digit. However, as inventories grew and become more complex, the element g became alphanumeric and a capital A was introduced for various newly added items. With passage of time, more elements were brought in and by the year 2000, upper case C was being used.Federal Supply Class
The initial subgroup of NSN abcd, is the National Supply Classification or the Federal Supply Class (FSC). It holds that similar items will always have numbers that are closely related no matter how the section is referred.  However, as the number of items has been increasing and the system has become complex, it has become very difficult to maintain similarity in numbers when items are similar too.National Item Identification Number
National Item Identification Number, also known as the NATO Item Identification Number (NIIN) comprises of a 9 digit code that uniquely identifies an item of supply among the NATO supplies. This NIIN is often used as a prefix before the FSC to make up a National Stock Number. It is important to remember here that only the NIIN identifies the item, the FCS merely indicates the general class of the item.NIIN comprises of the nine digits ef-ghi-jklm that are used for item identification.National Codification Bureau
The digits ef are used to records the country which first coded the item or which recognized it as important item for supply. This is basically used for the country of origin or the country where it was manufactured.The formal name of the field is CC for Country Code or NBC, which stands for National Codification Bureau. A simple example of this system is that US is 00, Japan is 30, Saudi Arabia is 70 and Australia is 66.History of NSN
NSN is actually a reformed shape of the Federal Stock Number (FSN) that lacked the national origin code labelled of ef, in the second subgroup.  Items that date back to 1975 and earlier were labelled with FSNs.The FSN system was brought into practice by the US Department of War before or during the Second World War. However, in 1998, this system was principally administered by the Defense Logistics Agency within the US Department of Defense.There are other stock numbering systems that are being use within the US Department of Defense but since 2005, NSN is the most common and clear system to identify the most standardized supply items.Federal Stock Number
A Federal Stock Number (FSN) consisted of an 11 digit numeric code that helped to identify items in the joint Army-Navy Catalog System. It was applied between 1949 and 1975, and after that it was replaced by the National Stock Number.The shift from FSN to NSN was carried out by adding on 00 between the first set of numbers. In other words; the federal supply class FSC and the second set of number.One such example is that 3139-121-6210 would become 3139-00-121-6210.Dramatized NSNs
Certain numbers have been referred in films and serials as if they were actually NSNs, especially in films and serials relating to military science fiction. However, it is important to remember that it is only done to lend an air of authenticity and nothing more....