We reinvestigate the twisted N=4 supersymmetry present in Schwarz type
topological field models. We show that Chem-Simons theory in three di
mensions can be untwisted to a kind of sigma-model with reversed stati
stics only in the free case. By dimensional reduction we define then t
he two-dimensional BF-model. We establish an analog result concerning
the untwisting, As a consequence of the definition through dimensional
reduction we find new fermionic scalar symmetries that have been over
looked so far in the literature. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.