This is the ValueSet that contains all the codes in ObservationEnvironmentalIntoleranceType (http://terminology.hl7.org/ValueSet/v3-ObservationEnvironmentalIntoleranceType) and ObservationEnvironmentalIntoleranceType (http://terminology.hl7.org/ValueSet/v3-ObservationEnvironmentalIntoleranceType). E.g. what you have to deal with if you get resources containing codes in either of them