This is the ValueSet that contains all the codes in STARS Message Type (https://starsapi.csiro.au/fhir-ig/stars/ValueSet/message-type-value-set) and STARS Message Type (https://starsapi.csiro.au/fhir-ig/stars/ValueSet/message-type-value-set). E.g. what you have to deal with if you get resources containing codes in either of them