  Global N=2 supersymmetry in four dimensions with a Fayet-Sohnius
hypermultiplet and a complex central charge is studied in N = 2 superspace. It
is shown how to construct the complete expansion of the hypermultiplet with
respect to the central charge. In addition the low-energy effective action is
discussed and it is shown that the `kernel' of the Lagrangian only needs an
integration over a `small' superspace to construct a supersymmetric action.
