Had to program my own charting of the actual spreads themselves. Like a Commodity spread is a line on most charting service programs, had to program actual bars like OHLC. It amazing with so many folks that trade options, I have never seen any commercially produced charting, but I did see some of this in the 80's for very short time. I often believe variations of trading never seen books on, much money in them. One of very few areas of no books is Commodity spreads, and when pits were open, many of those in the pits only traded spreads, and huge money in spreads, it is often a slower way to make money but margins are low and supply/demand of products that are grown or used have reoccurring patterns of life. Like the old saying in coffee, never sell it in July(south America's winter) and I have never started unless I was short long term.