This is the CodeSystem that contains all the codes in NHSN Spinal Fusion Approach (http://terminology.hl7.org/CodeSystem/NHSNSpinalFusionApproach) and NHSN Spinal Fusion Approach (http://terminology.hl7.org/CodeSystem/NHSNSpinalFusionApproach). E.g. what you have to deal with if you get resources containing codes in either of them