A computer processing system, comprising: a memory protection unit MPU; a plurality of region descriptors associated with the MPU, wherein the region descriptors include address range and translation identifier values for a respective region of memory; the computer processing system being characterized in that it further comprises: a translation identifier control indicator TIDCTL, wherein the translation identifier control indicator indicates whether or not globalization masking of a portion of one or more of the plurality of region descriptors is performed; control logic operable to determine whether the translation identifier control indicator is in a first state, and if the translation identifier control indicator is in the first state, to perform globalization masking of the portion of the one or more of the plurality of region descriptors corresponding to a second process being executed by the processing system to allow a first process being executed by the processing system to access a memory region allocated to the second process being executed by the processing system wherein the portion of the region descriptor that is masked is a translation identifier value TID; and wherein the computer processing system further comprises: a region globalization control enable indicator RGCEN; a process identifier PID; and control logic operable to determine whether the region globalization control enable indicator is in a first state, and if the region globalization control enable indicator is not in the first state, allow the first process to access the memory region allocated to the second process according to whether the TIDCTL indicator is in the first state. a memory protection unit MPU; a plurality of region descriptors associated with the MPU, wherein the region descriptors include address range and translation identifier values for a respective region of memory; the computer processing system being characterized in that it further comprises: a translation identifier control indicator TIDCTL, wherein the translation identifier control indicator indicates whether or not globalization masking of a portion of one or more of the plurality of region descriptors is performed; control logic operable to determine whether the translation identifier control indicator is in a first state, and if the translation identifier control indicator is in the first state, to perform globalization masking of the portion of the one or more of the plurality of region descriptors corresponding to a second process being executed by the processing system to allow a first process being executed by the processing system to access a memory region allocated to the second process being executed by the processing system wherein the portion of the region descriptor that is masked is a translation identifier value TID; and wherein the computer processing system further comprises: a region globalization control enable indicator RGCEN; a process identifier PID; and control logic operable to determine whether the region globalization control enable indicator is in a first state, and if the region globalization control enable indicator is not in the first state, allow the first process to access the memory region allocated to the second process according to whether the TIDCTL indicator is in the first state. a translation identifier control indicator TIDCTL, wherein the translation identifier control indicator indicates whether or not globalization masking of a portion of one or more of the plurality of region descriptors is performed; control logic operable to determine whether the translation identifier control indicator is in a first state, and if the translation identifier control indicator is in the first state, to perform globalization masking of the portion of the one or more of the plurality of region descriptors corresponding to a second process being executed by the processing system to allow a first process being executed by the processing system to access a memory region allocated to the second process being executed by the processing system wherein the portion of the region descriptor that is masked is a translation identifier value TID; and wherein the computer processing system further comprises: a region globalization control enable indicator RGCEN; a process identifier PID; and control logic operable to determine whether the region globalization control enable indicator is in a first state, and if the region globalization control enable indicator is not in the first state, allow the first process to access the memory region allocated to the second process according to whether the TIDCTL indicator is in the first state. a region globalization control enable indicator RGCEN; a process identifier PID; and control logic operable to determine whether the region globalization control enable indicator is in a first state, and if the region globalization control enable indicator is not in the first state, allow the first process to access the memory region allocated to the second process according to whether the TIDCTL indicator is in the first state.