This is the ValueSet that contains all the codes in Modality Type (http://fhir.ch/ig/ch-rad-order/ValueSet/ch-rad-order-modality-type) and Modality Type (http://fhir.ch/ig/ch-rad-order/ValueSet/ch-rad-order-modality-type). E.g. what you have to deal with if you get resources containing codes in either of them