Geometric tolerances-Geometric dimensioning and tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features.
All Around This Side of Parting Line - To apply a requirement to all features all around one side of a parting line, the graphical symbol for all around this side of parting line is indicated on the leader line.
All Over This Side of Parting Line - To apply a requirement to all features all over one side of a parting line, the graphical symbol for all over this side of parting line is indicated on the leader line.
Angularity - is the condition of a surface, axis, or centerplane, which is at a specified angle from a datum plane or axis.
Arc Length - indicating that a dimension is an arc length measured on a curved outline. The symbol is placed above the dimension.
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)