A concept that represents a set of ideas, abstractions, or things in the real world that can be identified with explicit boundaries and meaning and whose properties and behavior follow the same rules. It may be either a single or a group of associated concepts, abstractions, or things.

ObjectClass and Property are treated as a data model that can be mapped to like any other. This extension merely captures the ObjectClass element as a discrete code. The information conveyed here should also be conveyed in human-readable form in the mapping.map element.

unique id for the element within a resource (for internal references).

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition should be version specific. This will ideally be the URI for the Resource Profile defining the extension, with the code for the extension after a #.

Value of extension - may be a resource or one of a constrained set of the data types (see Extensibility in the spec for list).