the Information Security Automation Program (ISAP) and Security Content Automation Protocol (SCAP) that support and complement the approach for achieving consistent, cost-effective security control assessments. System security plan Agencies should develop policy on the system security planning process. NIST SP-800-18 introduces the concept of a System Security Plan. System security plans are living documents that require periodic review, modification, and plans of action and milestones for implementing security controls. Procedures should be in place outlining who reviews the plans, keeps the plan current, and follows up on planned security controls. The System security plan is the major input to the security certification and accreditation process for the system. During the security certification and accreditation process, the system security plan is analyzed, updated, and accepted. The certification agent confirms that the security controls described in the system security plan are consistent with the FIPS 199 security category determined for the information system, and that the threat and vulnerability identification and initial risk determination are identified and documented in the system security plan, risk assessment, or equivalent document. Certification and accreditation Once the system documentation and risk assessment has been completed, the system's controls must be reviewed and certified to be functioning appropriately. Based on the results of the review, the information system is accredited. The certification and accreditation process is defined in NIST SP 800-37 "Guide for the Security Certification and Accreditation of Federal Information Systems". Security accreditation is the official management decision given by a senior agency official to authorize operation of an information system and to explicitly accept the risk to agency operations, agency assets, or individuals based on the implementation of an agreed-upon set of security controls. Required by OMB Circular A-130, Appendix III, security accreditation provides a form of quality control and challenges managers and technical staffs at all levels to implement the most effective security controls possible in an information system, given mission requirements, technical constraints, operational constraints, and cost/schedule constraints. By accrediting an information system, an agency official accepts responsibility for the security of the system and is fully accountable for any adverse impacts to the agency if a breach of security occurs. Thus, responsibility and accountability are core principles that characterize security accreditation. It is essential that agency officials have the most complete, accurate, and trustworthy information possible on the security status of their information systems in order to make timely, credible, risk-based decisions