The angle formed by the occlusal rest and the vertical minor connector from which it originates should be:

An angle greater than 90 degrees fails to transmit occlusal forces, along the supporting vertical axis of the abutment tooth. This also permits slippage of the prosthesis away from the abutment, which can result in orthodontic-like forces being applied to an inclined plane on the abutment, with possible tooth movement. So the angle formed by the occlusal rest and the vertical minor connector from which it  originates should be less than 90 degrees.