This object specifies the name of the IP address pool group to
which this IP address pool belongs. If the value of this column
is the null string, then the pool does not belong to any IP
address pool group.
Observe that an implementation may reserve names for special IP
address pool groups. For example, an IP address may reserve the
name 'default' to denote the default Virtual Route Forwarding
(VRF) instance. An implementation should document reserved
names in a corresponding agent capabilities statement.