A chainwall is around the edges of the slab, you'll dig down about 18"(depending on who's doing it) and pour the concrete in the trench to support the edges, some even put "I"beams in the middle for support.
I'm a newbee here,
Looks good Matta5, if you don't mind me asking , how much did the building cost?
I'm wanting to build that size also. Are those 10' walls or 12'? On your slab, what type of chainwall did you use?