Several other dimensioning types are worth mentioning. These dimension types are not linear and serve specific purposes. Depending on your discipline, you may have a use for some of these types. For example, a mechanical part designer will make heavy use of radius and diameter dimension types, whereas a civil engineer will make use of datum dimension types.
Radius and Diameter Dimensions
Radius and diameter dimensions are used to dimension the size of an arc or circle, regardless of the type of object. If you create a polyline with an arc in it, for example, you can use either dimension type to dimension the arc. If you select the Center Mark check box in the Dimension Styles dialog box, the center mark will automatically be ...