on/off switch down by driver's foot

Does any one know what the on/off switch does located down by the driver's right foot? I thought it was the alarm bypass/valet mode, but I just got to playing around with it yesterday, and nothing happened. I can't seem to find anything on this in the manual. I've recently noticed that some of the newer Tahoes and Suburbans have this switch... any ideas? Thanks!!!

when you find out what this is please let us know
thanks

I've worked on many of these vehicles installing aftermarket items and not sure what you mean. I never seen it.