The Target Site value set is used with example binding for bodySite in IPS Radiology Observation. It overrides the FHIR core SNOMED CT Body Structures value set.

It isn't clear to me what the distinction between the two value sets is. One is codes where the concept "is-a 442083009 (Anatomical or acquired body structure)"; the other is codes where the concept "is descended from 442083009 (Anatomical or acquired body structure)." What is the purpose of this override?

(The Target Site value set is also used in IPS Immunization. It isn't clear that it is better than reusing the existing SNOMED CT Body Structures value set here either.)