This read-only Unsigned32 is the CoS value that should be applied to all packets from an untrusted port by a simple switching device that cannot classify traffic itself, and it only matters when rlCdpTlvExtendedTrust indicates no extended trust. An admin reads it to confirm what default class of service is being enforced for untrusted downstream traffic. For example, an admin using an inexpensive unmanaged phone that lacks its own QoS classification would rely on this field's advertised CoS value to mark that phone's traffic appropriately.