Monoclinic, Monoclinic Lattice
Index
The monoclinic structure has two unit cells. The primative cell (P) has fractional lattice points at the corners of the cell, and the base-centered cell (C) has additional fractional lattice points at the center of the basal planes of the unit cell. The primative cell has one lattice point associated with it. The base-centered cell has two lattice points.

The constraints on the primative vectors and angles for this system are:
a < b < c; a = g = 900, b may not be 900.