  The formal properties of the recently derived set of linearly independent
invariant amplitudes for the electromagnetic production of a pseudoscalar
particle from a spin-one particle have been further exploited. The crossing
properties are discussed in detail. Since not all of the amplitudes have simple
crossing behaviour, we introduce an alternative set of basic amplitudes which
are either symmetric or antisymmetric under crossing. The multipole
decomposition is given, and the representation of the multipoles as integrals
over the invariant functions weighted with Legendre polynomials is derived.
Furthermore, differential cross section and polarization observables are
expressed in terms of the corresponding invariant functions.
