This read-write object provides the Ethertype (Layer 2 protocol type) mask used to filter matching traffic in a Committed Packet Discard (CPD) flow classification rule. The mask is combined with a configured Ethertype value using bitwise AND operations to flexibly match IPv4, IPv6, MPLS, or other protocol families. A network engineer configuring quality-of-service policies would set this mask to selectively apply CPD (packet drop) rules to specific protocol types when network congestion occurs.