This is the ValueSet that contains all the codes in Performance Metric (http://hl7.org/fhir/us/davinci-vbpr/ValueSet/vbp-performance-metric) and Performance Metric (http://hl7.org/fhir/us/davinci-vbpr/ValueSet/vbp-performance-metric). E.g. what you have to deal with if you get resources containing codes in either of them