What is the "IGN---Batt" fuse in the IPM for?, and what position should the fuse be in...there are three holes for the two fuse terminals?

 

Oddly enough I was looking at something unrelated and noticed the same thing. My fuse is straddling the two options. And in the far right hole it actually looks like a buffer or jumper had been broken off in there so as not to allow someone to place the fuse in an incorrect position. Not sure why, or what it is, but apparently there's a purpose.

 

It appears that the fuse is always in the IGN (controlled by the ignition switch) unless you have a rear console, in which case you should also have an accessory relay in the IPM and then the fuse would protect that circuit. Then the fuse would go in the BAT position.

That assumes I'm reading the wiring diagram correctly

 

The fuse is for the 12V cigarette lighter/power port.
You can have it power up with the ignition or constant 12v unswitched.