The loop bounds a transport honours, in document ticks.
It lives in the timebase because that is all it is: two document positions and whether they are in force. Nothing here says how audio is produced or how a region is drawn, so the rung that runs the transport and the rung that draws the ruler describe the same loop with the same type rather than two structurally identical ones that have to be kept in step by hand.
A disabled loop keeps its bounds. enabled states whether wrapping happens, not whether a region exists, so turning a loop off and back on returns the user to the region they set up and a view keeps drawing it meanwhile.