Roof right concept

Roof right concept: Private builders viz-a-viz huda sector In case one owns a 2nd floor in Gurgaon (huda sector - builder floor), would he able to construct the 3rd floor (when the Far is increased) without the consent of lower floor occupants/owners? I would like to understand this for -- Private builders and for huda sector floors. Also, is it necessary that "WITH ROOF RIGHTS" clause be mentioned in the sale deed for the top floor? if yes, does that mean that a person with roof rights automatically becomes the owner of subsequent floors that he can construct now on top? I understand that the guy on the second floor has 'ROOF RIGHTS'. But what exactly does roof rights imply. Does it imply that any subsequent floors as and when cleared by the authorities to be built on top, will all belong to the person having roof rights?? Or is the implication of roof rights merely to the extent that the person can enjoy his terrace and use it as he likes with permissible one room construction but subsequently if 'n' number of floors are passed by the authorities then some benefit has to pass on to the guy on the ground floor.