This object serves as the VLAN ID index for protocol-based VLAN entries on Foundry switches, linking protocol-type matching to specific VLAN assignments. It identifies which VLAN a packet belongs to when classified by its protocol (e.g., IP, IPX, AppleTalk) rather than by port membership. A network operator uses this to create dynamic VLANs that automatically assign devices to VLANs based on the traffic protocol they generate.