Description: This attribute represents the filter group(s) associated with the CM signaled 'Upstream Drop Classifier Group ID' encodings during the registration process. UDC Group IDs are integer values and this attribute reports them as decimal numbers that are space-separated. The zero-length string indicates that the CM didn't signal UDC Group IDs. This attribute provides two functions: - Communicate the CM the configured UDC Group ID(s), irrespective of the CM being provisioned to filter upstream traffic based on IP Filters or UDCs. - Optionally, and with regards to the CMTS, if the value of the attribute UdcSentInReqRsp is 'true', indicates that the filtering rules associated with the Subscriber Management Group ID(s) will be sent during registration to the CM. It is vendor specific whether the CMTS updates individual CM UDCs after registration when rules are changed in the Grp object.