Orientation tolerances limit the orientation error of a feature’s surface, axis or centerplane relative to a specified datum (a perfectly flat and straight plane or line). The table shows the three orientation tolerances that are available and their associated symbols.
GD&T GEOMETRIC CHARACTERISTIC SYMBOLS
| Tolerance Type | Characteristic | Symbol | |
|---|---|---|---|
| For related features | Orientation | Angularity | a |
| Perpendicularity | b | ||
| Parallelism | f |