nvStructural allows you to define multiple drawing planes and work on any plane by selecting it from Draw section of the Home ribbon category. You can add new planes and modify/delete existing ones.
Default plane for 3D view is Z=0 plane. If you change the drawing plane in 3D view then your view will still be 3D but all of your clicks and grid snapped drawings will be automatically convert to coordinates that fall into your selected drawing plane.
If you are in a 2D view, ie, XY, YZ or XZ then you can choose any drawing plane that is parallel to the 2D view plane you have chosen.
On any drawing plane, snaps are controlled by the drawing grid chosen. You can change drawing grid and add/modify grid from Draw section of the Home ribbon category. Drawing grids are defined as grid spacings in u and v directions and optionally offset amouts to those spacings. Offsets are from the origin of the grid system which is the origin of drawing plane.