For purposes of this part:

(a) The terms Board or Agency mean the National Mediation Board, a collegial body composed of three members appointed by the President with the advice and consent of the Senate.

(b) The term meeting means the deliberations of at least two members of the Board where such deliberations determine or result in the joint conduct or disposition of official agency business, but does not include deliberations required or permitted or with respect to any information proposed to be withheld under by 5 U.S.C. 552b(d) or (e)/5 U.S.C. 552b(c).