'OSNAP
Defines object snap points.
You can specify object snap points at END[point], CEN[ter], NEA[rest], or MID[point] of objects. When you draw objects in this mode, the pointer snaps to the specified points.
You can specify more than one OSNAP mode at the same time (END and MID, for example, or END, MID, CEN). However, when you specify a mode, previous modes are automatically turned off.
Turn off all OSNAP modes by entering the mode NONE.
See also 'SNAP, 'GRID, 'ORTHO, Transparent Commands.