Extra position on ignition?
 

I have an XL package on my truck, so I have minimal options, but whoever owned my truck before me decided to put a couple random options on that it otherwise would not have had, such as my nicer looking head lights, and this odd spot on the ignition.

The ignition turns one more step after the "on" position before the "start" position. The glow plug light turns back on and my radio, interior lights, and heat or air conditioning shut off.

I would think that this was some sort of extra glow plug position...for whatever reason, but it seems to make it harder to start the truck in the cold if I use this feature.

...so my question:

What is this supposed to be?