Whether it be user-managed or system-managed, the installation controls whether it will allow a structure to be duplexed on a structure-by-structure basis. The DUPLEX keyword in the CFRM active policy applies both to user-managed and system-managed duplexing rebuild. Note that it is possible to initially define a policy that specifies DUPLEX(DISABLED) for a structure and then at a later time bring a new policy into the sysplex that allows or enables duplexing rebuild to be initiated for the structure and vice versa.