So, first, I do not know of a definitive dictionary of phrases. Also, each slicer uses different terms. Yuck. Now , the air gap is exactly what it sounds like. It does try to print a little higher off the raft. So, in theory, it does float. In reality, it does attach to the raft ( gravity and extruding and all that ) but creates a weaker bond than if it did not create that gap. Give it a shot. It's not perfect, but does help