If you are creating a feature that is not aligned with the existing edges of the part, you may want to create a datum plane as a horizontal or vertical reference that will be added. This is especially useful when you create radial feature patterns. When you create a datum plane as a reference, first select the direction you want the plane to represent (Top, Bottom, and so on) and then create it. The yellow side of the datum plane will face towards the specified side of the screen.