Metadata and access information about a code system. Metadata and access information about a code system. The category or type of resource that the code system represents. The subject domain of the ontology. The nature of the content of the ontology. The purpose for which the ontology was originally designed. A DirectoryURI that references the known versions of this code system. A reference to the code system version marked as CURRENT in the service instance. The local identifier that uniquely identifies the code system within the context of the implementing service. Note that the about URI is the globally unique identifier. A CodeSystemCatalogEntry read from a service instance. PSM A directory that summarizes a set of catalog entries. A synopsis of a CodeSystem along with information about how to access the complete resource. A directory URI that, when resolved, returns an ordered list of code system versions associated with this code system. versions may only be present if the service supports the CodeSystemVersion Query profile. A reference to the code system version marked as CURRENT in the service instance. The local identifier that uniquely identifies the code system within the context of the implementing service. Note that the about URI is the globally unique identifier. A set of code system catalog entries. An instance of CodeSystem that meets a specified filter criteria.