http://hl7.org/fhir/StructureDefinition/elementdefinition-suppress|5.2.0

If the extension is present on one of the named properties in a differential, the element property should be removed from the the corresponding snapshot.element during snapshot generation.
NameFlagsCardTypeDescription & Constraints
Extension
0..1Remove the element from the snapshot when generated
 
extension
?..0
 
url
?..?
 
value[x] *
1..?
 
 
valueBoolean *
1..?boolean