Hmmm ... not confusing at all ... when you have a "naked" 230SL frame.
Before stowing the top away the rear bow is folded upward to be locked in while the front part is still somewhat straight.
As can be seen in the right panel the rear bow presses against this buffer.
In this position one can also easily check whether the frame is bent because the rear bow should hit the buffers on both sides.
When folded completely and resting in the compartment (left panel) then I guess only the fabric is in contact.
Don't know whether this is the same on a 280SL frame.