This string is used to select one or more groups of devices to receive mass configuration operations. When cpsGroupCtrl.0 is null, SNMP operations are performed in the standard way for SNMPv1. When cpsGroupCtrl.0 is not null, the Cabinet (BiaIndex) and Slot (SlotIndex) index values that uniquely identify a device are ignored, and instead the operation is applied to all devices that have Groups variables that contain user- or system-defined keywords that match those in cpsGroupCtrl.0. The CfgMatch variables (cpsSlotDetail) for each of these devices will be yes(1). Advanced options are invoked by prepending one of the following command characters to the keywords in cpsGroupCtrl.0: 1) '.' means 'Pick-One'. When any 'Pick-One' operators are present in the Group Control String, then one or more of the keywords so marked must appear in the Device Group String of the slide-in device for configuration changes to be allowed. 'Pick-One' is the default operation that is used when no command character is present on a keyword. 2) '-' or '!' means 'Prohibited'. When any 'Prohibited' operators are present in the Group Control String, then if any of the keywords so marked appears in the Device Group String of the slide-in device, then no configuration changes are applied. 3) '+' is the 'Required' operator. When any 'Required' operators are present in the Group Control String, then all of the keywords so marked must appear in the Device Group String of the slide-in device for configuration changes to be allowed. 4) '*' is a Wildcard that matches zero or more characters. It is the only command character that does not need to appear at the beginning of the keyword. It is also the only one that can be used in combination with the others within a single keyword.