  We explicitly construct the SO(d,d) transformations of Ramond-Ramond field
strengths and potentials, along with those of the space-time supersymmetry
parameters, the gravitinos and the dilatinos in type-II theories. The results
include the case when the SO(d,d) transformation involves the time direction.
The derivation is based on the compatibility of SO(d,d) transformations with
space-time supersymmetry, which automatically guarantees compatibility with the
equations of motion. It involves constructing the spinor representation of a
twist that an SO(d,d) action induces between the local Lorentz frames
associated with the left- and right-moving sectors of the worldsheet theory.
The relation to the transformation of R-R potentials as SO(d,d) spinors is also
clarified.
