Enbridge (NYSE:ENB) and its pipeline customers are battling over a plan to cut overbooking of capacity cited as causing deep discounts of Canadian oil prices. The proposal, which is taking flak from the likes of IMO, XOM, SU, MPC and PSX, would shift how ENB calculates the amount of crude its shippers can nominate on the pipelines each month to a new system based on refinery capacities.