Reminds me of the Islamic concept of the Aura, which basically denotes body parts that should be covered in public. There's the so-called greater and the so-called lesser Aura. The greater Aura (= the body parts for which you commit a greater sin should you uncover yours in public or look at someone else's), goes from the navel to the knees. Thus, for a Muslim woman, it is less of a sin to go topless (as long as her pants cover all the way up to the navel) as it is to run around in a miniskirt or shorts.