This is the CodeSystem that contains all the codes in Occupation CDC Census 2010 (http://terminology.hl7.org/CodeSystem/PHOccupationCDCCensus2010) and Occupation CDC Census 2010 (http://terminology.hl7.org/CodeSystem/PHOccupationCDCCensus2010). E.g. what you have to deal with if you get resources containing codes in either of them