That's what I thought too but it doesn't seem to do anything. Can't find anything out there in webland either. Any owners know?
I just went down and fiddled with it. Press up to get to the menu. Cycle to the DTC setting. There is one for DTC on off and one for the DTC level. Hold down for 5 seconds. Then it will let you change your setting. Cycle through 1-4 and when you get the one you want hold down for 5 seconds. Hold up for 5 seconds to exit the menu.