This is the ValueSet that contains all the codes in Vital Signs Units (http://hl7.org/fhir/ValueSet/ucum-vitals-common) and Condition Status Trend Value Set (http://hl7.org/fhir/us/mcode/ValueSet/mcode-condition-status-trend-vs). E.g. what you have to deal with if you get resources containing codes in either of them