This is the ValueSet that contains all the codes in IHE ITI Sched Status Reason Codes (https://profiles.ihe.net/ITI/Scheduling/ValueSet/iti-sched-status-reason) and IHE ITI Sched Status Reason Codes (https://profiles.ihe.net/ITI/Scheduling/ValueSet/iti-sched-status-reason). E.g. what you have to deal with if you get resources containing codes in either of them