The proposed en-EU language tag is not allowed

[John Cowan]

RFC 3066bis does not permit en-EU, for the simple reason that EU is not
a ISO 3166-1 country code.  This list has no discretion in the matter;
we cannot register region codes except for those specified in the ISO
3166-1 and U.N. M.49 standards.

3166-1 codes are assigned by the ISO 3166/MA, but the MA also has no
discretion about the entities to be assigned codes.  Those entities are
specified by the United Nations Statistics Division.

There is no further point in discussing en-EU; registering it would be
ultra vires.

-- 
John Cowan  cowan at ccil.org  www.ap.org  www.ccil.org/~cowan
I am he that buries his friends alive and drowns them and draws them
alive again from the water. I came from the end of a bag, but no bag
went over me.  I am the friend of bears and the guest of eagles. I am
Ringwinner and Luckwearer; and I am Barrel-rider.  --Bilbo to Smaug