  We show that a complete embedded maximal surface in the 3-dimensional
Lorentz-Minkowski space $L^3$ with a finite number of singularities is, up to a
Lorentzian isometry, an entire graph over any spacelike plane asymptotic to a
vertical half catenoid or a horizontal plane and with conelike singular points.
  We study the space $G_n$ of entire maximal graphs over $\{x_3=0\}$ in $L^3$
with $n+1 \geq 2$ conelike singularities and vertical limit normal vector at
infinity. We show that $G_n$ is a real analytic manifold of dimension $3n+4,$
and the coordinates are given by the position of the singular points in $R^3$
and the logarithmic growth at the end. We also introduce the moduli space $M_n$
of {\em marked} graphs with $n+1$ singular points (a mark in a graph is an
ordering of its singularities), which is a $(n+1)$-sheeted covering of $G_n.$
We prove that identifying marked graphs differing by translations, rotations
about a vertical axis, homotheties or symmetries about a horizontal plane, the
corresponding quotient space $M_n$ is an analytic manifold of dimension $3n-1.$
