Of late. this Multi 2D bid opening is being increasingly used in tournaments all over the world.
It is the prerogative of the organising authority to permit or not this muti 2D opening.
Usually not permitted in local events below the level of state tourneys.
World Bridge Federation has issued a special note ( see its importance) on this > Here
Even though 99.9% of experts abide by the rules, a very few may use this system in state and below state level tourneys to further their chances of qualification.& Master Points (questionable)
It is our opinion, that all players in the world must know about " MULTI 2 D OPENING" so that they can use defense against it and also report to concerned authorities when used illegally. So we provide information about this:--
There are many variations of Multi 2D opening all of which we shall try to furnish here soon. Partnerships may decide defense against 2D opening after reading the following::-
ACBL has offered 2 defenses to MULTI 2 DIAMOND openings - -Here
David Stevenson's DIXON defense against 2D opening - - - - - - - - - - - - - - - - - Here
Mysterious Multi - How to play it & against it - Book by Mark Horton & Jan Van Cleeff - Here