An entry describes an IP address pool group.
The IP address pool manager creates an IP address pool group and
inserts it into the ciapPoolGroupTable when an entity sets the
value of an instance of ciapPoolContainedIn to a value that no
other IP address pool belongs to. Likewise, the IP address pool
manager removes an IP address pool group from the
ciapPoolGroupTable and destroys it when no IP address pools
belong to it.