This read-write DisplayString (1-64 chars), immutable once the entry becomes active, holds the domain name of the MGC, potentially registrable in DNS, that a session group communicates with. An admin cares because this name is what the group's sessions resolve to determine the MGC's IP address, and its immutability after activation means it must be set correctly at creation time. For example, an operator configuring a new session group must supply the correct MGC domain name at creation, since it cannot be corrected later once the group is active.