Creates a new layer.
New layers are numbered starting with this value.
Defines the center of the plane of symmetry for this layer. If you turn symmetry display on for this layer, the geometry will be reflected across this plane.
Defines the normal (perpendicular) direction for the symmetry plane. For example, 0.0 0.0 1.0 is a normal pointing up the Z axis, which creates a plane oriented along the X and Y axes.