http://hl7.org/fhir/StructureDefinition/documentreference-sourcepatient|5.2.0

The Patient Information as known when the document was published. May be a reference to a version specific, or contained.
NameFlagsCardTypeDescription & Constraints
Extension
0..1Source Patient Information
 
extension
?..0
 
url
?..?
 
value[x] *
1..?
 
 
valueReference *
1..?Reference