Field Selection

Any FHIR defined field can be used directly (e.g. this graphql against a human name field)

{ name { text given family } }

Polymorphic fields are represented by their JSON property name (e.g. for Observation.value[x]):

{ valueQuantity { value unit } }

Note: This is because the leaf names have to correspond to scalar types, so there is no use selecting all the variants at once