# Orientation Tolerance

Orientation tolerance determines the orientation for the form in relation to a reference. A datum is always necessary to indicate orientation tolerance; as such, it is a geometric tolerance for features related to datums.

## Parallelism

While it appears to be similar to flatness, parallelism involves a datum (reference plane or line).
The parallelism requirement specifies that two lines or planes are parallel.

Explanation of drawings
The plane indicated by the indication arrow must be parallel to datum plane A and be between two planes only 0.05 mm apart in the direction of the indication arrows.

## Perpendicularity

The perpendicularity requirement specifies the accuracy of how perpendicular a target is to the datum (reference plane or line).
Instead of degrees, millimetres are used as the unit for the value of perpendicularity indication.

Explanation of drawings
The plane indicated by the indication arrow must be within two parallel planes perpendicular to datum plane A and with a diameter of 0.03 mm.

## Angularity

The angularity requirement specifies how accurate an angle is to the datum (reference plane or line) when the specified line or plane is not 90 degrees.
Instead of degrees, the millimetre is used as the unit for the value of angularity indication.

Explanation of drawings
The plane indicated by the indication arrow must be theoretically exactly angled by 45 degrees to the datum plane A and between two parallel planes only 0.3 mm apart in the direction of the indication arrows.

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