Looking at the images on ebay, it would appear that the inner chainring is offset inward to make a gap between the crank mounting tab and the chain, and then the built in mounting stud is probably relieved on top as well for the chain. The outer ring probably has an undersized chainring bolt shaft for that clearance, and then has sloped faces that work like current Shimano chainrings to guide the chain to the left displaced inner ring.

The overall effect is that the inner ring's chainline is offset maybe 2-3mm.