Describes the subset of valid DDI objects used by an agency for a specified purpose. This may be the required and supported objects for a specific system, a profile for deposit in an archive, requirements at different points of production, etc. In addition to the standard name, label, and description the DDI Profile describes the intended application of the profile, its purpose, the version of XPath used in describing the supported objects, the DDI namespace (major and minor version numbers), a mapping of schema to prefixes (if different from the standard DDI model), a set of instructions for use of the profile, and a listing of used and unsupported objects. These objects may be constrained (i.e., change from optional to required), provided a fixed value, or provided a local name.