Use this setting to turn the symmetry effect on and off. This setting has the same effect as selecting Symmetry from the main menu.
This setting can, within limits, compensate for a not quite symmetrical distribution of guides. If, for example, you select guides on one side of the mirror plane, guides that lie the same distance away from the center on the other side will also be selected. If no guides are present within this distance, guides located a greater distance away will be searched for, depending on the value entered for Search.
Nevertheless, the best way to go is a perfectly symmetrical distribution of guides.
Use this setting to select a coordinate system to be applied to the mirror plane setting (Mirror) located next to it. You can select from:
Use this setting to define which mirror plane should be used (colored red in the example above).
If Custom is selected in the Coords setting, the coordinate system of the object placed into this field will define the coordinate system of the mirror plane.