55.—(1) Electromagnetic immunity
(2) The effect of an electromagnetic disturbance on a dimensional measuring instrument shall be such that—
(a)the change in measurement result is no greater than the critical change value as defined in paragraph (3); or
(b)it is impossible to perform any measurement; or
(c)there are momentary variations in the measurement result that cannot be interpreted, memorised or transmitted as a measuring result; or
(d)there are variations in the measurement result severe enough to be noticed by all those interested in the measurement result.
(3) The critical change value is equal to one scale interval.