This is the ValueSet that contains all the codes in ACH Monthly Encounter Class ValueSet (http://www.cdc.gov/nhsn/fhirportal/dqm/ig/ValueSet/ach-monthly-encounter-class) and ACH Monthly Encounter Class ValueSet (http://www.cdc.gov/nhsn/fhirportal/dqm/ig/ValueSet/ach-monthly-encounter-class). E.g. what you have to deal with if you get resources containing codes in either of them