  The Ramond-Ramond sector of double field theory (DFT) can be described either
as an O(D,D) spinor or an O(D-1,1) x O(1,D-1) bispinor. Both formulations may
be related to the standard polyform expansion in terms of even or odd rank
field strengths corresponding to IIA or IIB duality frames. The spinor approach
is natural in a (bosonic) metric formulation of DFT, while the bispinor is
indispensable for supersymmetric DFT. In these notes, we show how these two
approaches may be covariantly connected using a spinorial version of the DFT
vielbein, which flattens an O(D,D) spinor into a bispinor. We also elaborate on
details of the bispinor formulation in both even and odd D and elaborate on the
distinction between the IIA/IIB/IIA*/IIB* duality frames.
