http://hl7.org/fhir/StructureDefinition/observation-precondition|5.2.0
Other preceding or concurrent observations that must be known to understand the context and significance of the observation. For example, an fiO2 measure taken alongside of a SpO2 measurement. See the FHIR specification [Observation notes](http://hl7.org/fhir/observation.html#notes) section for additional guidance.
| type | destination |
|---|---|
| baseDefinition | http://hl7.org/fhir/StructureDefinition/Extension |
| type | http://hl7.org/fhir/StructureDefinition/Extension |
| Extension.value[x].type | http://hl7.org/fhir/StructureDefinition/Reference |
| Extension.value[x].targetProfile | http://hl7.org/fhir/StructureDefinition/Observation |