The rank for the purpose of assessment of service and disability elements of disability pension shall be the substantive rank or higher paid acting rank, if any , held by the individual or any of the following dates whichever is the most favorable:-
(a) the date of invaliding from service, or
(b) the date on which he sustained the would or injury or was first removed from duty on account of a disease causing his disablement, or
(c) if he rendered further service, and during and as a result of such service suffered aggravation of disability, the date of the later removal from duty on account of the disability.
Explanation. – In the case of an individual who on account of misconduct or inefficiency is reverted to a lower rank subsequent to the date on which the wound or injury was sustained or disability contracted, the rank for assessment of service and disability elements of disability pension shall be the rank held on the date of invaliding from service.