FIPS 201-3 Personal Identity Verification (PIV) for Federal Employees and Contractors is available at https://csrc.nist.gov/publications/detail/fips/201/3/final. A chronical of changes since the initial issuance of FIPS 201 is available in FIPS 201-3, Appendix E, Revision History.
Federal Information Processing Standard (FIPS) 201 entitled Personal Identity Verification of Federal Employees and Contractors establishes a standard for a Personal Identity Verification (PIV) system (Standard) that meets the control and security objectives of Homeland Security Presidential Directive-12 (HSPD-12). It is based on secure and reliable forms of identity credentials issued by the Federal Government to its employees and contractors. These credentials are used by mechanisms that authenticate individuals who require access to federally controlled facilities, information systems, and applications. This Standard addresses requirements for initial identity proofing, infrastructure to support interoperability of identity credentials, and accreditation of organizations issuing PIV credentials.
Security and Privacy: Personal Identity Verification
Laws and Regulations: Homeland Security Presidential Directive 12