Center Line

Center Line
An Imaginary line running perpendicular to the proscenium, from the back of the stage to the front edge of the apron and dividing the stage in half.
On Drawings
Denoted by a line consisting of a long dash followed by a single dot, and an entwined, stacked "CL" label.
In Reality
Often a TD, or LD will tape down a Center Line demarcation when installing the set, or the lights, as a way to find the proper points at which to set the pieces of scenery or lighting instruments.

The Center Line and Plaster Line (sometimes Smoke Pocket Line or Portal Line) form the two major axes upon which all other horizontal dimensions are based.