Frontal view (a), Oblique view (b) and Basal view (c) (dashed line shows the yaw rotation after modification). Pitch rotation is the angle between lateral occlusal plane to FH plane. Roll rotation is the angle formed by FH plane and bimaxillary first molar line. Yaw rotation is the angle between sagittal plane and midpalatal suture. Frontal ramus inclination is the angle between FH plane and line from lateral condyle point to lateral gonion point.