Heparin conjugates and methods of making and use thereof are disclosed. A locking pin inserts into the through holes of the side rail and through the apertures of the leg for locking the adjustable leg in the desired position, and the locking pin includes a flap member for holding the locking pin on the side rail. The effect is that nodes with internal slack are more often optimally placed in the schedule, reducing the need for rotating registers or register copy instructions.