Yellow belly is a co-dom and the super form is the Ivory.

It is a "visual" het that looks nothing like a normal IMO.
Flames from head to tail, head spot, belly with little squiggly lines running down the sides unlike normals that have wide squiggly lines.

Yellow belly belly shot


Normal belly shot


Yellow belly top shot showing flames


Normal top shot



Adult male yellow belly, you can sort of make out the head spot


Hope this helps...