I don't see how a lid has an interior bottom. A lid sits on top of a container so it should have just an interior top ('aqros) and an exterior top (yor). So are they thinking of it that the lid is no longer on the container but is instead sitting upside down? If so, does that mean that if a table were turned upside down you would not redefine all the surfaces based on which way they are now facing instead of which way they would normally face? That seems a bit confusing. Most people are not spatially oriented enough to do all that flipping around and still correctly identify where all the new orientations are for all the surfaces. One human IQ test in fact includes questions which most people find quite difficult that ask them to mentally turn an object in space then identify a new location for a given surface/side of the object.