Fix is a "static" position that fixs in the mind the feel of Zone 3 Ball Control (Direction), correct Impact Alignments especially of the Hands. In regard to the Plane, its two basic alignments are Direction and Angle. Most Important is its Direction, the Base Line of the Plane, which is usually the Line of Flight as established by the Target Line (Alignment A). The Plane Angle can change or be adjusted to the Plane Line (Alignment D).
Ya but, lets get ridiculously picky about it. Say, if I were to last second decide to switch to a Square Shoulder Plane from an Elbow Plane....would'nt you want to know that before aligning the Leading Edge of the Clubface? Hmm?