Coil can be generated with either closed or open end. Pressing Spacebar after the shape is digitized generates Coil with open end. This is useful for joining objects. Pressing Enter after the shape is digitized generates Coil with closed end.
For some machines, best results with Coil are achieved by sewing in a counterclockwise direction because when you sew in a clockwise direction, you are adding more twist to the yarn causing it to become tighter, distorting the Moss stitch loops. Refer to your machine handbook for more details.