This report specifies the data model and Extensible Markup Language (XML) representation for the Extensible Configuration Checklist Description Format (XCCDF) Version 1.2. An XCCDF document is a structured collection of security configuration rules for some set of target systems. The XCCDF specification is designed to support information interchange, document generation, organizational and situational tailoring, automated compliance testing, and scoring. The specification also defines a data model and format for storing results of security guidance or checklist testing. The intent of XCCDF is to provide a uniform foundation for expression of security checklists and other configuration guidance, and thereby foster more widespread application of good security practices.