Since when is any depiction of female nudity (nipples, etc) considered adult?

[Knowl Paine]

http://community.secondlife.com/t5/English-Knowledge-Base/Maturity-ratings/ta-p/700119

 

http://community.secondlife.com/t5/English-Knowledge-Base/Guidelines-for-creating-search-listings/ta-p/803947

[Knowl Paine]

http://community.secondlife.com/t5/English-Knowledge-Base/Maturity-ratings/ta-p/700119

 

http://community.secondlife.com/t5/English-Knowledge-Base/Guidelines-for-creating-search-listings/ta-p/803947

[Rolig Loon]

Some of the most popular items in my own Marketplace store are a collection of filmy nightgowns that I really need to photograph "as is" in order to do them justice in ads.  Of course nipples show.  I asked myself the same question about maturity levels a couple of years ago, and concluded that I had to list them as Adult.  At the moment, I can't find the document that convinced me.  The two links that Knowl provided come close but leave some ambiguity.  ( Maybe that's inevitable.  After all, who's to say for sure whether the Venus de Milo is artwork or a naked lady, and whether I am advertizing a nightie or providing a titillating image? )  Since we are on Linden Lab's turf, if they say it's Adult, it's Adult.  If they don't say but you want to play it safe, it's still Adult.