Just recently they changed BZA to GNWL from VSKP. Don't know the reason why SCR did it. But it surely helps many to catch GT towards delhi and Charimar, TN towards chennai. Even this berth vacancy happens to GT almost every day. VSKP-BZA quota is unpredictable one, the same happens to many train. Even VSKP-LTT/SNSI/KOLLAM all have VSKP and BZA in GNWL. No one knows from where tickets are booked.
Now famous trains VSKP GR, Tirumala are running with full END to END quota and sharing with very less station. SCR always changes this quota's...So now we can see it as GNWL in future again they may make it RLWL..I think its based on season and load.