http://hl7.org/fhir/StructureDefinition/codesystem-concept-comments|4.0.1

A comment that explains how this code is used in this context (where the value set is expected to be used).
element_idtypes
Extension
Extension.extension
Extension.url
Extension.value[x]
Extension
Extension.id
Extension.extension
Extension.url
Extension.value[x]