National Codification Bureau
The National Codification Bureaus or NATO Codification Bureaux (NCB) are a NATO organization that oversees the management of the NATO Codification System (NCS). It is governed by NATO Allied Committee 135 (AC/135), with each member nation's National Codification Bureau controlling and issuing its own unique NATO Stock Numbers. NATO or European Union membership is not required to do so. Non-NATO (or "Partner") countries can be allowed to join if recommended, vetted, and approved by AC/135.
Countries that participate in the NATO Codification System (NCS) follow common standards and techniques to assign NATO Stock Numbers (NSNs) to items of supply in their defense inventory. The National Codification Bureau (NCB) within each country centrally assigns their national NSNs. The assignment of an NSN denotes a distinctive item of supply; to eliminate confusion, the number will never be re-used.
The NATO Stock Number (NSN) system was implemented by the United States on September 30, 1974, replacing the United States' Federal Stock Number system (1949-1974). It was managed by the Defense Integrated Data System in 1975.
All NSNs are uniform in composition, length, and structure. Each is represented by a 13-digit number (in the format: 1234-56-789-10/11/12/13), which can be divided into two parts:
NATO Supply Classification Group
The first four digits are the NATO Supply Classification Group (NSCG) code. This relates the item to the NATO Supply Group (digits 1 & 2) and NATO Supply Class (digits 3 & 4) of similar items that it belongs to. For examples, see List of NATO Supply Classification Groups.
The next 9 digits make up the National Item Identification Number / NATO Item Identification Number (NIIN). The NIIN has lately become alphanumeric (digits and uppercase letters) due to the vast array of items in the NSN, recently adopting the use of the uppercase letter C in place of "12" in 2000.
The first two digits indicate the assigning country's NCB code - also informally called a "Country Code" or "Nation Code". Each country has its own two-digit NCB code, which were granted in the order the NCB system was adopted by that country. The United Kingdom (99), Australia (66) and New Zealand (98) are the exceptions; as a courtesy they were granted their status before the rest of NATO reviewed and accepted the NCB. The United States uses "00" and "01" because they invented the system and were using it before the rest of NATO. NCB code "00" generally indicates an item in US inventory before 1974 (when the NSN was adopted by the US) and "01" usually indicates an item placed in US inventory after 1974. Canada's NCB "20" and "21" have a similar purpose. The numbers "02" through "10" are unassigned to reserve future catalog numbers for the United States' use. NATO-issue items use "11" and United Nations-issue items use "44". The number 69 was assigned but is no longer registered in use - perhaps belonging to a controversial partner like Taiwan or Iraq.
The final seven digits (dubbed the "non-significant number" - but used without an acronym to avoid it being confused with the "NATO Stock Number") are random. They indicate the code number for the unique item in that country's inventory. It will never be reused or changed to avoid confusion. The seven digits of the "non-significant number" are divided into parts by a hyphen; the first three digits are the interfix number of the batch of code numbers and the last four digits are the unique code number of the item.
The Federal Stock Number (FSN) was the codification system used by the US Government from 1957 to 1974. It was 11 digits long and was the same number as the NSN (see National Stock Number), minus the two-digit NCB code. The digits "00" were later added in the place of the NCB digits to virtually all FSN numbers to create compliant American 13-digit NSN numbers.
The FSN was officially replaced by the NATO Stock Number beginning on September 30, 1974.