  A Ginzburg-Landau-like functional is proposed reproducing the main low-energy
features of various possible high-Tc superconducting mechanisms involving
energy savings due to interlayer interactions. The functional may be used to
relate these savings to experimental quantities. Two examples are given,
involving the mean-field specific heat jump at Tc and the superconducting
fluctuations above Tc. Comparison with existing data suggests, e.g., that the
increase of Tc due to the so-called interlayer tunneling (ILT) mechanism of
interlayer kinetic-energy savings is negligible in optimally-doped Bi-2212.
