what the blogers have mentioned is partially correct. There is a difference between Lower Berth Quota and preference of berth. Most of the blogers are giving correct information about preference of the berth at the time of booking.Here you can give preference of your choice, the same will be entered and if avilable alloted from the general quota. any one can opt for this. But Lower Berth seats/berths are alloted only for passenger "male 60 yrs & above and female 45 yrs & above who travel alone"