Thanks for the advice!

The charting system will allow selection of arbitrary contracts for each leg, including intermarket, and calendar spreads. The calendar spread feature will allow selection of months using a wizard which allows for easily selection of spread formula like

(1 x nearest July Corn) - (1 x following-December Corn)

and other variations based on calendar months. Therefore, it is easy to create a 'standing' formula for "Corn Bull Spread" or similar.

What sorts of calendar spreads are of interest?

I find the spread charts very interesting, even if I am not interested in entering a trade. The spread charts reveal relationships between markets which are otherwise hidden within the the noise of market action.

Thanks!
Mike