Tone Curve Assist

The new DPPv2.2 comes with two new Adjustments: Tone Curve Assist (TCA)-Standard and TCA-High.
They impact the images substantially, and I wonder if anyone knows what they do, and how they work? With the rather dark 400D RAW images, the effect of TCA is to move the histogram much further to the right, much like the Shadow/Highlight control in PS-CS2 works.
For samples, check out these images on my website: http://gandini.unm.edu …ography/PhotoTe​ch/XTi.htm

cheers, phil

Maybe the link below will help? When you go there, click on Tutorials along th etop, then the Tone Curve III one towards the bottom in blue letters.

http://photoworkshop.c​om/canon/dpp2/index.ht​ml