This is the ValueSet that contains all the codes in LOINC Codes (http://hl7.org/fhir/ValueSet/observation-codes) and VDOR Toxicology Summary Tests Value Set (http://hl7.org/fhir/us/vdor/ValueSet/vdor-toxicology-summary-tests-vs). E.g. what you have to deal with if you get resources containing codes in either of them