This read-only InetAddressType most likely reports whether the address of the scheduler that initiated the last test, given in the paired avCnaTpMonLastTestSchedAddr object, is IPv4 or IPv6; the MIB provides no description text for this particular object, so this is inferred from its name and its sibling. An admin would use it the same way as other address-type objects, to correctly parse the accompanying scheduler address value. A monitoring script reading avCnaTpMonLastTestSchedAddr would first check avCnaTpMonLastTestSchedAddrType to know how to interpret the address bytes.