  It is shown how extended supersymmetry realised directly on the (2,2)
semichiral superfields of a symplectic sigma model gives rise to a geometry on
the doubled tangent bundle consisting of two Yano F structures on an almost
para-hermitian manifold. Closure of the algebra and invariance of the action is
discussed in this framework and integrability of the F structures is defined
and shown to hold. The reduction to the usual (1, 1) sigma model description
and identification with the bi-quaternionic set of complex structures and their
properties is elucidated. The F structure formulation should be applicable to
many other models and will have an equivalent formulation in Generalised
Geometry.
