Constrains cursor movement to the horizontal or vertical directions.
ORTHO affects pointer movement, but not keyboard entry.
Horizontal is defined as parallel to the X axis; vertical is parallel to the Y axis.
You can toggle ORTHO to be ON or OFF by pressing the F8 function key, or by double-clicking ORTHO on the status bar.
See also 'SNAP, 'GRID, 'OSNAP, Function Key Toggles, Transparent Commands.