Table 1: Messages for pruning algorithm.

Name Attributes Remark CRQ Sender.Level For nodes to find out all their children by this CRQ (Children Request) message Sender.PID Sender.GPID CMT Sender.PID For nodes to maintain or update their valid children Sender.BPID CMTR BP_Flag Reply for CMT CDN   For nodes to notify their parents when they detach from the tree CDNR   Reply for CDN