The federal catalog system is responsible for naming, describing, classifying, and numbering all items carried under centralized inventory control by the  DoD  and  the  civil  agencies  of  the  federal government. In all supply functions from purchase to final disposal, only one identification may be used for each item. This system also serves as an economy measure. Instead of the Army, Navy, Air Force, and civil agencies each purchasing and maintaining large stocks of materials, all agencies can make use of centralized stocks. North Atlantic Treaty Organization (NATO) countries also use the federal catalog system. STOCK AND CONTROL NUMBERS Stock and control numbers are used to identify and order material in the supply system. The identification numbers are known as    national stock numbers (NSNs),    NATO stock numbers (a variation of the NSN)    Navy item control numbers, and    local item control numbers. A  definition  and  description  of  the  types  of  stock and   control   numbers   are   stated   in   the   following paragraphs. National Stock Numbers The  national  stock  numbers  (NSNs)  are  the  most common numbers used to identify material. An NSN is a 13-digit number consisting of a 4-digit federal supply classification   (FSC)   code   number   and   a   9-digit national item identification number (NIIN). Figure 7-1 shows the typical NSN format. The FSC number identifies an item by commodity or  description.  The  first  two  digits  of  the  FSC  are called  the  FSC  group,  and  the  last  two  digits  of  the FSC   are   called   the   FSC   class.   Figure   7-2   is   an example   of   the   FSC   system.   The   first   two   digits d e n o t e   t h e   g r o u p   o r   m a j o r   d iv i s i o n   o f   t h e commodities; for example, group 53 is hardware and abrasives. The last two digits (for example, 05) denote the   class   or   subdivision   within   a   group.   In   other words,   screws   are   a   class   or   subdivision   in   the hardware and abrasives group. The  NIIN  identifies  each  item  of  supply  used  by the DoD and NATO. The NIIN relates to identification data  that  makes  an  item  of  supply  different  (as  far  as DoD  is  concerned)  from  every  other  item  of  supply. The amount and type of identification data depend on the item and its intended use. Although the NIIN is part of the NSN, it is used independently to identify an item. Except   for   identification   lists,   most   federal   supply catalogs are arranged in NIIN order. NATO Stock Numbers A  NATO  agreement  provided  for  the  adoption  of the  United  States  NSN  system  as  the  basis  for  the NATO   item   identification   system.   A   NATO   stock number is identical to an NSN with the exception of the national  codification  bureau  (NCB)  code.  The  NCB code  consists  of  the  first  two  digits  of  the  NIIN  (see fig.  7-1).  The  NCB  code  either  identifies  the  country that  assigned  the  stock  number  or  indicates  that  the stock  number  is  used  by  two  or  more  countries.  For example,  an  NCB  will  be  00  or  01  to  indicate  the 7-2 Stores Account Cognizance Symbol Material Control Code Federal Supply Group Federal Supply Classification (Group) Federal Supply Classification (Class) National Codification Bureau Code National Item Identification Number National Stock Number Special Material Identification Code 1H Q    5330-00-010-4960-X3 MRP3f0701 Figure 7-1. Typical NSN format. GROUP 53 Hardware and abrasives 5305 - Screws 5306 - Bolts 5307 - Studs 5310 - Nuts and washers 5320 - Rivets 4810 - Valve solenoid 4820 - Valve angle 4010 - Wire rope, steel 4020 - Rope, fibrous 4030 - Hook, guy GROUP 48 Valves GROUP 40 Rope, cable, chain, and fittings MRP3f0702 Figure 7-2. Classes of material within stock groups.