.topic 0x10000000
 Specify the letter of the alphabet that will be used for the next Datum Label. The default letter is A. Successive labels are in alphabetic order.


.topic 0x10000001
 Specify the letter of the alphabet that will be used for the next Section Label or Detail Label. The default letter is A. Successive labels are in alphabetic order. (Drawing section and detail views do not share the same letter.)


.topic 0x10000002
 Composite Frame.  A composite frame allows for the location of a profiled feature or circular pattern and, at the same time, the control of form and orientation. The entire frame is doubled in height; the top half is the locating tolerance zone, and the bottom half is the form and orientation (or feature-related) tolerance zone. The first compartment of the feature control frame holds a geometric characteristic symbol that is common to both.


.topic 0x10000003
 Projected Tolerance Zone. A tolerance zone that is recommended when there are variations in perpendicularity of threaded or press-fit holes which could cause interference when mating a part. The PTZ is located at true position and extends away from the primary datum at the threaded feature.