http://hl7.org/fhir/StructureDefinition/servicerequest-precondition|5.2.0

The condition or state of the patient, prior or during the diagnostic procedure or test, for example, fasting, at-rest, or post-operative. This captures circumstances that may influence the measured value and have bearing on the interpretation of the result.
element_idtypes
Extension
Extension.extension
Extension.url
Extension.value[x]
Extension
Extension.id
Extension.extension
Extension.url
Extension.value[x]