6.—(1) The external packaging of a unit packet or container packet of hand rolling tobacco may contain a calibration mark but only if both of the following conditions are met.
(2) Those conditions are—
(a)that the calibration mark appears only so far as it is necessary for the automated manufacture of the packaging of the hand rolling tobacco, and
(b)that the calibration mark, if visible or otherwise detectable, is as inconspicuous as possible so far as is consistent with its function in connection with that automated manufacture.