  We explore the scaling description for a two-dimensional metal-insulator
transition (MIT) of electrons in silicon. Near the MIT, $\beta_{T}/p =
(-1/p)d(\ln g)/d(\ln T)$ is universal (with $p$, a sample dependent exponent,
determined separately; $g$--conductance, $T$--temperature). We obtain the
characteristic temperatures $T_0$ and $T_1$ demarking respectively the quantum
critical region and the regime of validity of single parameter scaling in the
metallic phase, and show that $T_1$ vanishes as the transition is approached.
For $T<T_1$, the scaling of the data requires a second parameter. Moreover, all
of the data can be described with two-parameter scaling at all densities --
even far from the transition.
