be available for opposite elements in the case of waisting or barrel ng of the surface. See Fig. 6-1.
Figures 6-2 and 6-3 show examples of cylindrical features where ali circular element» of the ¡surface arc to be within the specified size tolerance; however, the boundary of perfect form at MMC may be violated. This violation is permissible when the feature control frame is associated with the size dimension or attached to an extension of the dimension line. In this instance, a diameter symbol precedes the tolerance value and the tolerance is applied on either an RFS or MMC basis. Where necessary and when not used in conjunction with an orientation or position tolerance, the straightness tolerance may be greater than the size tolerance. Where the straightness tolerance is used in conjunction with an orientation tolerance or a position tolerance, the specified straightness tolerance value shall not be greater than the specified orientation or position tolerance values. The collective effect of size and form variation can produce a virtual condition or outer or inner boundary equal to the MMC size plus the straightness tolerance. When applied on an RFS ba-
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