NameRequiredExtensibledoco
.. Condition
... Slices for extension
.... extension:age_at_diagnosis
.... extension:age_at_onset
... clinicalStatus Condition Clinical Status Codes
... verificationStatus ConditionVerificationStatus
... severity
.... coding
..... system
..... code Severity Value Set
... bodySite
.... coding
..... system
... subject
.... identifier
... Slices for onset[x]
.... onset[x]:onsetDateTime

doco Documentation for this format