Chapter 9 Profile Tolerances 329 The drawing shown in Example 9-14 can also have the surfaces controlled with a flatness geometric tolerance without using a datum reference. When the feature control frame leader points to the phantom line, all of the surfaces are jointly controlled. For example, if there are a total of four additional raised surfaces behind the two that can be seen in the front view, the note 6X is placed below the feature control frame. A top view would also be required to provide dimensions to the 6 raised features. When there are several coplanar surfaces, it can be desirable to establish two surfaces as datum planes with a common profile tolerance, such as the datum features labeled A and B in Example 9-14. Other coplanar surfaces can be controlled with a profile tolerance relative to both datums by placing the letters A-B in the feature control frame. The profile tolerance zone applies to all surfaces, including the datums. Refer to Example 9-15. The Meaning 0.6 profile tolerance zone Simulated datum A-B 0.3 profile tolerance at datum plane The Drawing Example 9-15. When there are several coplanar surfaces, it can be desirable to establish two surfaces as datum planes with a common profi le tolerance and control other surfaces with a profi le tolerance specifi ed to both datums. A note specifying the number of surfaces or the continuous feature symbol can be used. Profile of Plane Surfaces Profile tolerancing can be used to control the form and orientation of planar surfaces. For example, profile of a surface can be used to control the angle of an inclined surface in relationship to a datum, as shown in Example 9-16. Notice in Example 9-16 that the required surface must lie between two parallel planes 0.1 mm apart equally split on each side of a true plane that has a basic angular orientation to a datum.