I would have expected 'paper colour' to reflect er...the colour of the paper stock being used. So that an ink will be the combination of the paper colour and the ink. However I have used a gradient with 'white' or in other words no CMY or K in the ink value. However changing the paper colour of the document still has the applied gradient showing white, where I would have expected the 0% ink in the 'white' to now show the 'paper colour'. Further after changing the paper colour, no other applied colours seem to be changing even if I apply a light tint it seems to knock out the 'paper colour' which doesn't make sense..