What is true about the EoMPLS control word?

A.
It is different for .1q tagged versus untagged Ethernet frames.

B.
It indicates the class of service of an EoMPLS packet.

C.
It is only used for .1q tagged packets, to convery the tag to the remote end.

D.
The first 4 bits are 0 as to not alias an IP packet.

E.
There is no such a thing as EoMPLS control word.