PCI Slot wrong way round?

I have an old mobo (for amd thunderbirds) that has a pci slot in between the agp slot and the rest of the pci slots that is the wrong way round and is blue instead of being white?!!
Why is this?

Cheers

http://www.intel.com/update/departm...top/dt05001.pdf
probably a cnr slot, could be one of a couple others, via made their own expansion slot for a while, i dont know why they bother, any hardware for these is expensive and usually not any better. like the amr slot on some motherboards, supposed to be for less expensive modems that use system resources instead on having their own . big laugh, they are total crap.