  We generalize the prequantization central extension of a group of
diffeomorphisms preserving a closed 2-form \omega (\omega-invariant
diffeomorphisms) to an abelian extension of a group of diffeomorphisms
preserving a closed vector valued 2-form \omega, up to a linear isomorphism
(\omega-equivariant diffeomorphisms). Every abelian extension of a simply
connected Lie group can be obtained as the pull-back of such a prequantization
abelian extension.
