326 GD&T: Application and Interpretation Copyright Goodheart-Willcox Co., Inc. This results in a position tolerance boundary that is .005″ from the profi le boundary on all sides. The .005″ applied on each side results in a total width .010″ tol- erance when opposite sides are considered. Applying position tolerances in combination with profi le tolerances is explained in more depth in Chapter 11. Previous standards required the notation BOUNDARY beneath the position tolerance feature control frame. The notation is no longer required, but ASME Y14.41 continues to show it in some fi gures. That suggests that its use is allowable. Position Tolerance with No Datum Feature Reference Datum feature references are required on most positional tolerances, but there are excep- tions, as has been briefl y explained in this chapter. See Figure 8-40. The given part has three cylinders that are 2.000″ diameter and they lie on a com- mon axis. A position tolerance of .002″ diameter is applied to defi ne the amount of position variation that is permitted between the three features. There is no datum feature reference in the position toler- ance feature control frame that is applied to these three cylinders. The specifi ed position tolerance establishes a tolerance zone framework that is an axis through the three cylinders. It has no constraint requirement relative to any other feature. This practice is allowed only where the toleranced features are identifi ed as a datum feature and are referenced as the primary datum feature in other feature control frames. Goodheart-Willcox Publisher Figure 8-40. A position tolerance applied to coaxial cylinders may not include any datum references if the features serve as a primary datum feature.