A couple of session issues

One thing I couldn't get to the bottom of is PS(define_sid) and the define_sid logic in php_session_start(). I understand the code, but I couldn't understand why we define SID in certain cases to contain valid data, and sometimes just an empty string. It's also being used in session_adapt_uris() later. The other issue is a suggestion I want to pitch - right now, if sessions are started after the headers are already sent, we'll get a nice headers-already-sent error. If we have trans_sid enabled (which we will most probably, from now on) - we can check whether the headers are already sent, and if they are, move to use trans_sid instead. Any comments? Zeev