The standard organizes geometric controls into several functional categories to manage different aspects of part geometry: Typical Controls Straightness, Flatness, Circularity, Cylindricity
Controls the physical placement of features relative to each other or a datum. Profile of a Surface, Profile of a Line Controls the boundary of a feature's outline. Runout Circular Runout, Total Runout Controls variation in a surface when rotated about an axis. Building Blocks of the Language Dimensioning and Tolerancing ASME Y14.5M-1994
Imaginary, mathematically perfect points, axes, or planes used as reference points for measurements. mathematically perfect points