The value of tmnxSubAuthPlcyRadServCoAOnly specifies
if this RADIUS server is restricted to sending Change-of-Authorization
messages only (not authentication requests).
There can be maximum 16 of these CoA-only servers associated with
a single authentication policy.
If the value of tmnxSubAuthPlcyRadServCoAOnly is equal to 'true', the
value of tmnxSubAuthPlcyAcceptAuthChange is not considered anymore
for this RADIUS server.