[en] QCD sum rules calculations of the form factors governing the semileptonic decays of charmed and beauty mesons are reviewed. In particular, the predicted dependence of the various form factors on q² is discussed, and the way of how it can be obtained for the form factors of vector and axial currents. In some cases the q² dependence, computed by QCD sum rules, is different from the outcome of lattice QCD. A Tau-Charm Factory could be an efficient tool to study this aspect of the charmed meson transitions. (author). 28 refs., 2 figs., 1 tab