http://hl7.org/fhir/StructureDefinition/derivation-reference|5.2.0

References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.

Name	Card	Type	Description & Constraints
Extension	?..?		References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
extension	0..1		Source reference.
extension	?..0
url	?..?
value[x] *	1..?
valueReference *	1..?	Reference
extension	0..1		Element containing text.
extension	?..0
url	?..?
value[x] *	1..?
valueString *	1..?	string
extension	0..1		Starting position.
extension	?..0
url	?..?
value[x] *	1..?
valueInteger *	1..?	integer
extension	0..1		Number of characters.
extension	?..0
url	?..?
value[x] *	1..?
valueInteger *	1..?	integer
url	?..?
value[x]	?..0