and the other ones aren't, and, it wishes to use a consistent format for the part numbers of all of the parts it uses. Therefore, the user devises its own part numbering system. In such a system, the user may use the part number "HSC0424PP" for that screw. There are also some national and industry-association initiatives which help producers and consumers codify the product based on a unified scheme to establish a common language between industrial and commercial sectors. For example: The Iranian national classification and codification system known as Irancode is a 16 digit code to codify the products in a nationally unified manner. The U.S. government, and most especially its Department of Defense, has standardized various part numbering systems over the decades for it and its suppliers to use, such as the AN (Army-Navy) and MS (Military Standard) hardware classification and numbering systems. The Aerospace Industries Association maintains the NAS system (National Aerospace Standards), which is gradually replacing the AN and MS systems. The ASME provides a codification of fastener specifications in B18.24 Part Identifying Number (PIN) Code System Standard for B18 Fastener Products. Significant versus non-significant part numbers In general, there are two types of part numbering systems: significant (a.k.a. "intelligent") and non-significant (a.k.a. "non-intelligent"). In a significant part numbering system, the part numbers are assigned intelligently, according to an encoding system, and thus they give an indication of salient characteristics of the component. For example, a screw may have the part number "HSC0424PP"; in this case, the letters indicate characteristics of the component: H = "Hardware" S = "Machine Screw" C0424 = "4-40, 3/4" long" PP = "Panhead Phillips" In a non-significant part numbering system, part numbers are assigned in some other fashion, such as sequentially or arbitrarily. For example, a screw may have the part number "1002", which may not tell the user anything about its thread size, length of shank, or drive type. Significant part numbering systems are easier to use if you are trying to identify an item through the use of its code inside your company rather than a long description; however, many variations can start to appear when the code is used by other companies, which may be your distributors, and then people can become confused. Non-significant part numbers are easier to assign and manage. You can still create a structure where you can have a category and then a sequential