(1) Permanent, physical disabilities for the purpose of deduction under clause (c) of section 27A,-
(i) permanent physical disability shall be regarded as a permanent physical disability if it, falls if any one of the categories specified below, namely:-
(a) permanent physical disability of not less than 40 per cent in one limb, or
(b) permanent physical disability of more than 60 per cent, if two or more limbs, or
(c) permanent deafness with hearing impairment of 71 decibels and above, or
(d) permanent and total loss of voice.
(ii) blindness shall be regarded as permanent physically disability, if it is incurable and falls in any of the categories specified below, namely:-
(2) Mental retardation for the purpose of deduction under clause (e) of section 27A, -
Mental retardation shall be regarded as mental retardation if intelligence quotient is less than 50 on a test with a mean of 100 and a standard deviation of 15 such as the Wechsle scale.