Union of http://www.iana.org/assignments/media-types and http://www.iana.org/assignments/media-types
This is the CodeSystem that contains all the codes in MIME (http://www.iana.org/assignments/media-types) and MIME (http://www.iana.org/assignments/media-types). E.g. what you have to deal with if you get resources containing codes in either of them