Straightness: straightness refers to the condition that the actual shape of the straight line elements on the part maintains an ideal straight line. This is what is commonly referred to as straightness. Straightness is the maximum allowable variation of an actual line from an ideal straight line. That is, what is given on the drawing is used to limit the allowable variation range of the actual line processing error.

Flatness: flatness refers to the actual shape of the plane elements of the part and the condition of maintaining an ideal plane. This is what is commonly referred to as flatness. Flatness is the maximum allowable variation of the actual surface from a flat surface. That is, it is given on the drawing to limit the allowable variation range of the actual surface processing error.

Roundness: roundness refers to the actual shape of the elements of the circle on the part, equidistant from its center. That is commonly referred to as the degree of roundness. Roundness is the maximum allowable variation of an actual circle from an ideal circle on the same cross-section. That is, it is given on the drawing to limit the allowable variation range of the actual circle processing error.

Cylindricity: cylindricity means that the points on the cylindrical surface contour of the part are equidistant from their axes. Cylindricity is the maximum allowable variation from an actual cylindrical surface to an ideal cylindrical surface. That is, what is given on the drawing is used to limit the allowable variation range of the actual cylindrical surface machining error.

Line profile: line profile refers to the condition that any curve of any shape maintains its ideal shape on a given plane of the part. Line profile refers to the allowable variation of the actual contour of a non-circular curve. That is, what is given on the drawing is used to limit the allowable variation range of the actual curve processing error.

Surface profile: surface profile refers to the condition in which any shaped surface on a part maintains its ideal shape. Surface contour refers to the actual contour line of a non-circular surface and the allowable variation from the ideal contour surface. That is, what is given on the drawing is used to limit the variation range of the actual surface processing error.

Parallelism: parallelism refers to the condition that the actual elements being measured on the part remain equidistant relative to the datum. This is what is commonly referred to as maintaining parallelism. Parallelism is: the maximum allowable variation between the actual direction of the measured element and the ideal direction parallel to the datum. That is, what is given on the drawing is used to limit the allowable variation range of the measured actual elements from the parallel direction.

Verticality: verticality means that the measured element on the part maintains a correct 90° angle relative to the datum element. That is, what is usually called the degree of orthogonality between two elements. Verticality is: the maximum allowable variation between the actual direction of the measured element and the ideal direction perpendicular to the datum. That is, it is given on the drawing to limit the maximum allowable variation range of the measured actual elements from the vertical direction.

Inclination: inclination refers to the correct condition in which the relative directions of two elements on a part maintain any given angle. Slope is the maximum amount of variation allowed between the actual direction of the feature being measured and its ideal direction at any given angle to the datum.

Symmetry: symmetry means that the two symmetrical center elements on the part remain in the same central plane. The degree of symmetry is: the amount of variation allowed by the center plane of symmetry (or center line or axis) of the actual element from the ideal plane of symmetry. The ideal symmetry plane refers to the ideal plane common to the datum symmetry plane (or center line or axis).

Coaxiality: coaxiality means that the measured axis on the part remains on the same straight line relative to the reference axis. This is commonly referred to as the degree of coaxiality. Coaxiality is: the allowable variation of the measured actual axis relative to the reference axis. That is, it is given on the drawing to limit the allowable range of variation of the actual axis being measured from the ideal position determined by the reference axis.

Position: position refers to the accuracy of points, lines, surfaces and other elements on the part relative to their ideal positions. Position degree is: the maximum allowable change in the actual position of the measured element relative to the ideal position.

Circular runout: circular runout means that the rotating surface on the part maintains a fixed position relative to the datum axis within a limited measurement plane. Circular runout is: the maximum allowable variation within a limited measurement range when the actual element being measured rotates around the reference axis for a full circle without axial movement.

Total runout: total runout refers to the amount of runout along the entire measured surface when the part continuously rotates around the reference axis. Total runout is: the maximum amount of runout allowed when the actual element being measured continuously rotates around the datum axis while the indicator moves relative to its ideal contour.