Superfield lagrangian quantization with extended BRST symmetry

We consider possible superfield representations of extended BRST symmetry f or general gauge theories within the principle of gauge-fixing based on a g enerating equation for the gauge functional. We examine admissible superfie ld choices for an extended antibracket and delta-operator with given algebr aic properties and show that only one of these choices is compatible with t he requirement of extended BRST symmetry realized in terms of supertranslat ions along Grassmann coordinates. We demonstrate that this realization lead s to the gauge-independence of the S-matrix. (C) 2001 Published by Elsevier Science B.V.