  The multifractal properties of electronic eigenstates at the metal-insulator
transition of a two-dimensional disordered tight-binding model with spin-orbit
interaction are investigated numerically. The correlation dimensions of the
spectral measure $\widetilde{D}_{2}$ and of the fractal eigenstate $D_{2}$ are
calculated and shown to be related by $D_{2}=2\widetilde{D}_{2}$. The exponent
$\eta=0.35\pm 0.05$ describing the energy correlations of the critical
eigenstates is found to satisfy the relation $\eta=2-D_{2}$.
