Once I had to travel in Secunderabad Rajdhani, As first AC had waiting, 2AC was avlb. So I opted for 2AC. When I boarded the train I enquired from the TTE, he told me that one berth is available, bit he cautioned me that no Sr Ctzn concession is available. He however confirmed that as per rules, he has to charge the difference of 2ac and 3ac fare, if I have age proof.