N=2 central charge superspace and a minimal supergravity multiplet
  We extend the notion of central charge superspace to the case of local supersymmetry. Gauged central charge transformations are identified as diffeomorphisms at the same footing as space-time diffeomorphisms and local supersymmetry transformations. Given the general structure we then proceed to the description of a particular vector-tensor supergravity multiplet of 24+24 components, identified by means of rather radical constraints. 
G. Akemann, R. Grimm, M. Hasler and C. Herrmann