  If the Lorentzian norm on a maximal surface in the 3-dimensional
Lorentz-Minkowski space $R_1^3$ is positive and proper, then the surface is
relative parabolic. As a consequence, entire maximal graphs with a closed set
of isolated singularities are relative parabolic.
  Furthermore, maximal and minimal graphs over closed starlike domains in
$R_1^3$ and $R^3,$ respectively, are relative parabolic.
