The Right Hand is placed on the Club in its Vertical Condition, i.e., perpendicular to the Horizontal Plane. This alignment is mandatory for the ideal Right Forearm Flying Wedge and its 90 degree support of the Left Arm Flying Wedge.
I guess it's time to show my ignorance, but I don't understand what you mean here, Yoda. I understand what perpendicular is, but I guess I'm unsure what the "Horizontal Plane" is. The only plane I'm familiar with is lying on an angle. The right arm shouldn't hang straight down, naturally, at address?
In the meantime, I'm going to go see if I can find this in the Yellow Book.
I think what he means by vertical or perpendicular is to place the hands vertical against one of the three basic planes - per hinge action.