sajhafan, I got your mail. Like Everest01 said they will put a stamp on your passport which will be valid for 24 hrs but I disagree on the fact that we cannot go outside. Basically you are already out once the stamp is placed on the passport. I travelled recently ( July - August 2013). After the stamp was placed on my passport, myself with my wife and some frens went to a guest house for that night ( 14 hrs transit in Kunming) and then came to the airport the next morning. One incident I want to share was I forgot my money bag ( $2000) in rest room ( I know pretty funny) in Shanghai...But luckily I got it back ( good citizen turned it back or I don't know) from the police( took foto of handing over and stuff hehe).