Discussions

I´ve added an ipart in 'shopping cart page' to opt between 'Single Payment' or 'Automatically pay future renewals' and
would like to give a discount when user selects one of those but before submitting the cart.

Questions:

1. How can I trigger an event when user picks some option to give a discount before submitting the cart?
2. Where (table) are these 2 option stored?. Are they properties of the cart 'json' structure?