(1) In communications, the system that issues a request to establish communications with another system.
(2) In distributed data management (DDM), a system containing an application programme that requests access to data in another system.
(3) The system that sends information in a network of systems that exchange objects and data. See also target system.
(4) The system that currently owns the production copy of an independent disc pool in a cross-site mirroring (XSM) environment. Changes to the production copy of an independent disc pool are replicated to all mirror copies of the independent disc pool that exist on backup nodes within the recovery domain.