Providing indirect data addressing in an input/output processing system where the indirect data address list is non-contiguous

I / O processing system I / O subsystem in the system for providing indirect data address, method and computer program product are disclosed. The computer program product includes a storage medium of the type which stores instructions for execution by the processing circuit can be read by a processing circuit to perform the desired method. The method receives a control word for an I / O operation. Wherein the control word includes an indirect data address for the data associated with the I / O operation. The indirect data address includes a starting location of a list of storage addresses that collectively specify the data, the list spans two or more non-contiguous storage locations. Data is gathered responsive to the list. The data collected are transmitted to a control unit in the I / O processing system.