@Kamesh Krishnamoorthy: Re# 141869-0
Earlier, it was like, if vacancy exists in SL as well as 3AC., , then upgradation was not done from SL - 3AC.
SL had to be in waiting for upgradations to take place(Vacancy in 3AC exists).
I guess, now the scenario is like, even if seats are available in SL and 3AC, passengers are upgraded from SL - 3AC.