This Standard is intended to provide all users (manufacturers, distributors, design and configuration, parts control, inventory control, test and maintenance functions) with the capability to identify externally threaded, internally threaded, and non-threaded fastener products by a pre-selected order of coding as specified herein. The B18 PIN is a self-contained code, with distinct identification linkage to individual ASME B18 fastener product standards. The PIN code concept provides for direct traceability back to the applicable B18 product standard. In case of conflict with this document and B18 product standard, the B18 product standard shall take precedence. This Standard is not intended for use as a substitute for the correct usage of the B18 standards for fastener selection and specification. The PIN code is intended as an alternative to the plain text product callout as prescribed in the "Designation" or "Ordering" section of the source B18 product standard. The existence of a PIN code for B18 fastener description is not intended to imply that all products described are available. A few B18 fasteners cannot be thoroughly identified using the 18 digit system defined in this standard. If the user does not find the PIN needed in the body of this standard consult the Appendix where special PIN systems have been created to specifically identify those items. If the sought after PIN for the desired B18 fastener is not in the Appendix, notice should be sent to the secretary of B18 so that the item can be addressed in the next revision of this standard.