you are right... in fact 50% quota is reserved for Gondia-Nagpur section (GNWL) and 50% for Nagpur to BSL/MMR section....
I wanted to book a confirm ticket from AK- SUR... it was showing waitlisted (RLWL)... but i checked again after reading your answer and found that GNWL still had seats available...
booked a confirmed ticket from ITR to SUR with Boarding stn as AK... thanks a lot for providing a very important hint...