Snap to points (for example, named points, geometry points, geometry face centre,
geometry edge centre, mesh vertices and grid) in the 3D view.
Press and hold down Ctrl+Shift while hovering
with the mouse cursor over the model.
Note:
An active snapping point is indicated by a black dot.
Special snapping points near the mouse cursor are indicated by blue
dots.
A preview of the geometry is displayed as a green wireframe model
(when snapping to a point as part of geometry creation).
Left click on a blue dot and release Ctrl+Shift
to snap to that point.
When snapping to align a new workplane, the history of the starting point and
the route followed to the destination points, affects the orientation of the
workplane (for example the orientation of an edge).