Projected Tolerance Zone - applies to a hole in which a pin, stud, screw, etc., is to be inserted. It controls the perpendicularity of the hole to the extent of the projection from the hole and as it relates to the mating part clearance. The projected tolerance zone extends above the surface of the part to the functional length of the pin, stud, and screw relative to its assembly with the mating part.

—投影公差區(qū)

Tangent Plane - indicating a tangent plane is shown. The symbol is placed in the feature control frame following the stated tolerance. —切平面

Free State Variations - is a term used to describe distortion of a part after removal of forces applied during manufacture. —自由狀態(tài)的變化

Diameter - indicates a circular feature when used on the field of a drawing or indicates that the tolerance is diametrical when used in a feature control frame. —直徑

Basic Dimension - used to describe the exact size, profile, orientation or location of a feature. A basic dimension is always associated with a feature control frame or datum target. (Theoretically exact dimension in ISO)

—基本尺寸

Reference Dimension - a dimension usually without tolerance, used for information purposes only. It does not govern production or inspection operations. (Auxiliary dimension in ISO) —參考尺寸

Datum Feature - is the actual component feature used to establish a datum.

—基準特征

Dimension Origin - Signifies that the dimension originates from the plane established by the shorter surface and dimensional limits apply to the other surface. —尺寸原

Conical Taper - is used to indicate taper for conical tapers. This symbol is always shown with the vertical leg to the left. —圓錐錐度

Slope - is used to indicate slope for flat tapers. This symbol is always shown with the vertical leg to the left. —斜坡度