Some times, you can conveniently fix an additional coordinate system to more well create drawings. This non–world coordinate system, known as a user coordinate system, is so widely utilized that UCS now refers to all coordinate system in Auto-CAD.
Why would you want to diverge from the standard WCS? Well, the most common ground is that it’s much easier to calculate and enter coordinates if they’re based on the plane you want to work on in 3D.
Suppose that you’re modeling an old-fashioned, wedge-shaped rubber doorstop and you want to add the manufacturer’s logo to the sloping surface of the wedge. It isn’t simple if you stay in the WCS, but Auto-CAD lets you set a new UCS based on that sloping surface. After the UCS is made current, you draw in it just as you draw in the WCS.
Just create a UCS that’s aligned appropriately. You can look up this procedure in the online help system, but here’s a quick hint: Click the UCS icon in the lower-left area of the screen to make “grips” appear at the origin and the ends of the axis indicators. Then drag the icon by its grips to set a fresh UCS.