Specify an object snap quickly and conveniently from a shortcut menu.
The object snap menu is displayed at your cursor location when you hold down SHIFT and click the right mouse button or the equivalent button on another pointing device.
The default object snap menu lists object snaps and tracking options. If you want to change the options, you can modify a customization file. The main customization file thatâ€™s shipped with the product is acad.cui.
in the Customization Guide