sentence: following this , several provisional , green paper versions , pren 3910 p1 & p2 , were produced by working-group c2-gt9 of the association europeene des constructeurs de materiel aerospatial ( aecma ) ( now asd-stan ) , before its development also ceased in 1996-7 ( following the withdrawal of the french delegation , who held the chair of aecma c2-gt9 at the time ) .