You can change the range for placing an object by editing these parameters.
Footprint (FTPT) defines the area of the object in xz plane and the interactions around the area, such as placement, intersection, passing, etc.. Whereas the values in Bounding box under Visual Proxy and Model corresponding to 3 dimensional size of the object.
 = minimum x,  = min y,  = min z,  = maximum x,  = max y,  = max z.
These values seem to be changed when new mesh is imported.
Here is an example. This is a wall decor. I deleted the dropshadow group. The values in Visual Proxy and Model are almost same. If an object has dropshadow, the range define in Model includes that of dropshadow (not in Visual Proxy).
This object can't be moved higher than 3.0 (full height of walls) and lower than 0 (below floor) even with alt key and moveObjects on. I want to make it move beyond these limits, so I changed its y values by +/- 0.5.
This edited version can be moved beyond the ceiling and floor height to +/- 0.5.