Its not a Ching Sling - Ching Sling uses 3 swivels/studs, with the extra one going just forward of the floorplate.

I only know this because I read the Art of the Rifle about 6 weeks back... Jeff originally used what he named the CW sling after Carlos Widmann of Gautamala, who it sounds like copied an old British system - a loop from the front swivel to the floorplate swivel only.

Mr Ching, a student at Gunsite Academy, upgraded the CW sling by adding the extra bit to include stock swivel, to make it easier to carry.