This is the ValueSet that contains all the codes in US Public Health ValueSet Priority (http://hl7.org/fhir/us/ph-library/ValueSet/us-ph-valueset-priority) and US Public Health ValueSet - Priority (http://hl7.org/fhir/us/ph-library/ValueSet/us-ph-valueset-priority). E.g. what you have to deal with if you get resources containing codes in either of them