[en] Starting from the Kazama-Neveu-Nicolai-West action for the open superstring we obtain, by a consistent truncation, the minimal gauge invariant action for the Neveu-Schwarz sector. For the Ramond sector the ''(k, k+1) form'' fields, which are not eliminable without the introduction of non-localities, contain Goldstino modes involved in the Higgs effect by which fermions acquire a mass. In both the NS and the R sector the Gliozzi-Olive-Scherk projection operators must, for consistency, be modified to include a dependence upon the ghosts for the world-sheet supersymmetry