Given a Galois branched cover f: Y --> X of smooth curves over a mixed characteristic (0,p) DVF, one can take a reduction bar{f} of f to characteristic p. Under certain circumstances, bar{f} will be inseparable on some irreducible components of Y, and we can naturally associate a differential form to each of these components, called a deformation datum. One thinks of these forms as somehow keeping track of the information that is lost when we reduce mod p. We will discuss the construction of deformation data in detail, and show how a simple concrete example due to Bouw, Wewers, and Zapponi leads to the positive solution of the local lifting problem for the dihedral group of order 2p when the conductor h is less than p.