NIST SP 800-116
FASC-N Identifier - The FASC-N shall be in accordance with [TIG SCEPACS]. A subset of FASC-N, a FASC-N Identifier, is a unique identifier as described in [TIG SCEPACS]. Section 2.1, 10th paragraph of [TIG SCEPACS] states "For full interoperability of a PACS it must at a minimum be able to distinguish fourteen digits (i.e., a combination of an Agency Code, System Code, and Credential Number) when matching FASC-N based credentials to enrolled card holders." Also, Section 6.6, 3rd paragraph of [TIG SCEPACS] states, "The combination of an Agency Code, System Code, and Credential Number is a fully qualified number that is uniquely assigned to a single individual". The Agency Code is assigned to each Department or Agency by Special Publication 800-87, Codes for the Identification of Federal and Federally-Assisted Organizations [SP800-87]. The subordinate System Code and Credential Number value assignment is subject to Department or Agency policy, provided that the FASC-N Identifier (i.e. the concatenated Agency Code, System Code, and Credential Number) is unique for each card.