The 3D Locus tool places a 3D locus onto the drawing. These can be handy reference points that you can use when drawing and measuring objects. You can also use 3D loci as pivot points or fixed points for rotating and aligning objects.
Since 3D loci are not actual visible objects, there may be times you want to make them invisible, especially in a rendered view.
To hide 3D loci:
The Only in Wireframe option shows 3D loci in Wireframe mode, but hides them in all other render modes, such as OpenGL, Final Quality RenderWorks, etc. The Never option hides 3D loci in all render modes.