# CNSSI 1253 **Entity class:** National-security systems instruction ## Definition **Committee on National Security Systems Instruction 1253**, *Categorization and Control Selection for National Security Systems*, applies the NIST Risk Management Framework and SP 800-53 control catalog to National Security Systems. It supplies NSS categorization, baselines, overlays, parameter values, and tailoring guidance. CNSSI 1253 demonstrates convergence with specialization: national-security systems use a common federal control vocabulary while retaining stricter or mission-specific implementations. ## Relationships - **issued by:** [[wiki/Committee on National Security Systems|CNSS]]. - **builds on:** [[wiki/NIST SP 800-37|NIST SP 800-37]] and [[wiki/NIST SP 800-53|NIST SP 800-53]]. - **applies to:** [[wiki/National Security System|National Security Systems]]. - **supports:** [[wiki/ICD 503|ICD 503]] implementation and [[wiki/Security Controls and Control Overlays|control overlays]]. ## Sources / Provenance - [NIST macOS Security Compliance Project — CNSS document index](https://pages.nist.gov/macos_security/more-information/additional-documents/) - [NIST — SP 800-53A references to CNSSI 1253](https://csrc.nist.gov/pubs/sp/800/53/a/r5/final)