This special identifier both enables and identifies the OSPF process on the device - setting it from zero to any nonzero value turns OSPF on and unlocks further OSPF configuration, while setting it back to zero disables OSPF entirely and wipes all existing OSPF configuration; once nonzero, it can't be changed to a different nonzero value without first clearing it to zero. Administrators use this as the master on/off switch and process identifier for OSPF on the device, mirroring the same "process ID" concept used in the CLI. Setting this object from 0 to 1 would turn OSPF on and open up the rest of the OSPF configuration objects for use, while setting an already-active process ID back to 0 would tear down the entire OSPF configuration.