cmProxyArpRowStatus is a read-write enumeration activating or destroying proxy ARP on a given DSL port, valid only when that port is configured in one of the IP netmodels, and the description notes attempting to enable it on an incompatible netmodel triggers a 'DB_INCONSISTENT_VALUE' error while changing the netmodel later automatically deletes an active proxy ARP row. An administrator enables this on a subscriber's DSL port when that customer's IP addressing scheme requires the system to answer ARP requests on the customer's behalf. For example, an operator setting up a customer on an IP netmodel needing proxy ARP would set cmProxyArpRowStatus to active(1) for that line's PII, but changing that customer's netmodel afterward to an incompatible one would automatically remove this entry.