Description: The ID of the terminal that contains the SNMP agent. This may, or may not, identify the root of the topology tree. The root of the toplogy tree is really an abstraction, defined as the terminal having the lowest ID number in a UMC network. If the umc1TopologyTable has any rows in it, then the smallest terminal ID is considered the root of the topology tree. If the umc1TopologyTable empty, then (and only then) can the assumption be made that this variable holds the ID of the root of the topology tree, since it identifies the only known terminal. Unfortunately, all bets are off if the *real* root of the topology tree is unreachable at the time of autodiscovery. The LET is 1, RST1 is 2, RST2 is 3, etc.)