Carrying on with the cinema hall usability...
Every time we bought movie tickets from E Square multiplex, we used to wonder how near our seats were going to be from the screen. Even though the guy inside the box office showed us the layout and the position of our seats on his computer screen, by the time we came out of the que it was forgotten. Then it was all a guessing game and then a self consolation that E square's first row is kinda far from the screen. The problem with E Square seat numbers were that they had the back row as the 'A' row.
'A' row being the first row is more usable for the movie goers who wants to know how far his seat is from the screen. PVR has 'A' as the front row.
What is the difference?
Say you got a ticket with a seat number I25 at PVR. Now if you know that the the front row is 'A', then its easy for you to figure out that your seat is on the 9th row from the screen which is pretty decent. And if you also know how many seats are there in a row then you kinda find out the exact position too (which is less important of course).
Now consider if 'A' is the back row, like in E Square. Even if you know that you are going to sit at the 9th row from the back, you really don't have a clue that how many rows are there in the auditorium and hence how near are you from the screen.
Any other advantages?
The box office guy doesn't have to show you the auditorium layout to make you know the seat positions. This saves the ticketing time. There can be a note at the counter which says 'A' row is the front row and then you can do your own math to figure out where you will be sitting.