Having spent four days traversing across Chennai in buses, I must confess, it is worse than one of those MENSA puzzle books to understand the bus-numbers. However, I believe that I have concluded how the damn things are labeled:
Initially, the buses were given normal numbers - 1,2,3,4,5,... all the way up to 99.
Then, rather than entering the realm of 3 digit numbers, which undoubtedly would be too difficult for those morons to count, they decided to now use alphabets (or perhaps this was their idea of teaching the general populace english). So now the buses were numbered 5A, 5B, 5C, etc. (thus 5 is different from 5A, which is different from 5B, etc.).
After this, the chief ministers decided that the bus numbers must possess their initials. So now there were buses like JJ5A, JJ5B, etc.
When the new government came to power, to remedy this, they added letters to the buses before the numbers also. So this gave rise to bus numbers like M5G.
When they had run out of numbers and alphabet combinations, they now decided to use double alphabets. So the numbers now were things like AA5A, etc.
Finally, they now also decided to use special characters. Thus we have numbers like 5G*, which, incidentally, goes to all places 5G does not. So the * is some sort of a complement, a ' as we say in set theory.
In addition to this, we have some more alphabet combinations like PP (Point to Point), LS (Limited Stops), etc.
So note the following combination: AM5G* PP, which is different from the following combinations: AM5G*, AM5G, M5G, 5G, M5, AM5, A5, 5, 5*, etc. with the PP or LS appended to all
