About Draft Entities in a Drawing
You can add draft entities to a drawing at any time. Using commands in the Sketch menu, you can create various geometry types: lines, circles, arcs, splines, ellipses, points, and chamfers. Yo can use draft entities in the following ways:
• Use the same referencing and geometric constraints as in 3D Sketcher.
• Group separate entities with each other so they move as one.
• Group drafted geometry with a view, so that it scales up or down with the view scale.
Entities read in to a drawing from an IGES, DXF, or SET file are considered to be draft entities.
You can set preferences for some of snapping and sketching behaviors in the drawing environment from within the Sketch Preferences dialog box (Click > 
Sketcher Preferences). You can set up common grid, angle and snapping properties for the drawing tools. You can also set sketching preferences, like activating chain sketching or parametric sketching.
Sketcher Preferences). You can set up common grid, angle and snapping properties for the drawing tools. You can also set sketching preferences, like activating chain sketching or parametric sketching.