http://hl7.org/fhir/StructureDefinition/data-absent-reason|4.0.1

Provides a reason why the expected value or elements in the element that is extended are missing.
NameFlagsCardTypeDescription & Constraints
Extension
0..1unknown | asked | temp | notasked | masked | unsupported | astext | error
 
extension
?..0
 
url
?..?
 
value[x] *
1..? DataAbsentReason (required)
 
 
valueCode *
1..?code DataAbsentReason (required)