See: Pramathanath Sastry, Correction to: "Regular differential and equidimensional scheme-maps", J. Algebraic Geom. 14 (2005), 593--599.
Summary: This corrects a sign error in the paper "Regular
differential and equidimensional scheme-maps",
J. Algebraic Geom. 1 (1992), 101--130 by J. Lipman and P.
Sastry