Observation values used to indicate a knowledge subject of interest for which knowledge content is requested (e.g., a medication, a laboratory test, a medical condition).
\nThis value set includes codes based on the following rules:
http://snomed.info/sct
http://terminology.hl7.org/CodeSystem/v3-MSH
http://terminology.hl7.org/CodeSystem/v3-icd9cm
http://terminology.hl7.org/CodeSystem/v3-icd10
http://www.nlm.nih.gov/research/umls/rxnorm
http://hl7.org/fhir/sid/ndc
http://loinc.org