This is the ValueSet that contains codes in both US Public Health ValueSet - Message Significance Category (http://hl7.org/fhir/us/ph-library/ValueSet/us-ph-valueset-message-significance-category) and US Public Health ValueSet - Message Significance Category (http://hl7.org/fhir/us/ph-library/ValueSet/us-ph-valueset-message-significance-category).