The VLAN 0 Priority Tagging Support include empowers 802.1Q Ethernet edges to be sent with the VLAN ID label set to nothing.

Model use cases:
BT FTTP circuits
MOCA arrangements

+1 for this

I guess it has been discussed before. It could probably be implemented by simply changing the value validation on VLAN interfaces, I think.
(allow a VLAN with ID 0)

Please focus discussion about this in one thread. I suggest that a moderator close this thread and if possible merge the unique posts in this thread with the original (at least the most recent identical request).

Feature request: VLAN 0 Priority Tagging Support