Takes a value from the valueset listed in the model to indicate the data value in the containing model is a change from a previous instance of the same model.

This model is intended to constrain values from OBX-8 in a lab result HL7 message. Because OBX-8 is overloaded to contain multiple types of data, we need a way to tell which kind of code is sent (abnormal flag, delta flag, or ordinal interpretation.

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).