Discount calculation questions

Hi!

I have been struggling for several days now with trying to implement changes to the way discounts are calculated in the shop. I have been successful with article discounts but not with discounts relating to the whole basket (discount assigned to user group). In oxbasket.php I found two methods doing discount calculations:
[ul]
[li]calculateBasket: this calls a whole bunch of discount related submethods, but even if a delete the call to all of them nothing changes in the basket.
[/li][li]getBasketSummary: this seems to be the one doing the calculation when the basket is open.
[/li][/ul]

My questions are:
[ol]
[li]What is the purpose of the calculateBasket method?
[/li][li]What is the relation between the two methods?
[/li][/ol]