from irfca
Commercial Classification: Stations are also classified based on their commercial importance into categories 'A', 'B', ... etc., which is rather confusing. The particular classification scheme used has to be inferred from the context. In the commercial importance classification scheme, a non-suburban station with annual passenger earnings over Rs 60 million is a Category A station. Category B stations have earnings between Rs 30 million and 60 million. Any suburban station not falling into the 'B' category is considered to be a Category C station. Non- suburban stations with earnings between Rs 10 million and 30 million are Category D stations while non-suburban stations with lower earnings fall into Category E. Halt stations are classified as Category F stations. Interestingly, the...
more... commercial classification determines many of the construction aspects of the station: Stations of Category A or C have high level platforms, while those in categories B and D have low level platforms. Statiosn of categories E and F have only rail-level platforms.