This is the destination of this Reachable Address, an Address Prefix, following the replaceOnlyWhileDisabled and ManualOrAutomatic behaviors. It is the actual OSI destination prefix this reachability entry describes, and because it follows replaceOnlyWhileDisabled, an admin correcting a mistyped prefix must first disable the entry before the prefix value itself can be changed rather than editing it in place while active. For example, fixing a typo'd NSAP prefix in an existing reachable-address entry requires the admin to disable that entry first, since the MIB will not allow the prefix to be modified while it is still active.