  The conformal algebra provides powerful constraints, which guarantee that
renormalized conformally covariant operators exist in the hypothetical
conformal limit of the theory, where the $\beta$-function vanishes. Thus, in
this limit also the conformally covariant operator product expansion on the
light cone holds true. This operator product expansion has predictive power for
two-photon processes in the generalized Bjorken region. Only the Wilson
coefficients and the anomalous dimensions that are known from deep inelastic
scattering are required for the prediction of all other two-photon processes in
terms of the process-dependent off-diagonal expectation values of conformal
operators. It is checked that the next-to-leading order calculations for the
flavour non-singlet meson transition form factors are consistent with the
corrections to the corresponding Wilson coefficients in deep inelasitic
scattering.
