Each of the datum features referenced in a DRF constrains one or more translational and/or rotational DOF of the DRF. Ideally, a planar datum feature is parallel to the axis of rotation of any rotational DOF that it constrains. The DRF has poor repeatability if that angle is approaches 90 degrees. This advisor message is displayed when the angle is greater than 60 degrees.

The figures below show two similar examples in which datum feature C in DRF A|B|C constrains the rotation of part about datum A axis. In the example on the left, datum feature B and the datum A axis of the DRF are parallel. As you can imagine, as the angle between axis A and datum feature C approaches 90 degrees, the DRF has poor repeatability. In the example on the right, the angle between datum feature C and the A axis is 65 degrees. Assuming that DRF_RotAngle is set to 60 degrees (the default value), the example shown to the right would cause the test associated with this advisor message to fail and the message would be displayed.