We derive short UIR's of the OSp(8/4,R) superalgebra of 3d N=8 superconformal
field theories by the requirement that the highest weight states are
annihilated by a subset of the super-Poincare odd generators. We then find a
superfield realization of these BPS saturated UIR's as "composite operators" of
the two basic ultrashort "supersingleton" multiplets. These representations are
the AdS4 analogue of BPS states preserving different fractions of supersymmetry
and are therefore suitable to classify perturbative and non-perturbative
excitations of M-theory compactifications.Comment: refrences adde