49.—(1) The measurements and calculations required by this Part must be made—
(a)in accordance with Schedule 4; and
(b)in accordance with designated standards(1), where available.
(2) Where designated standards are not available, the measurements and calculations referred to in paragraph (1) must be made in accordance with methods which —
(a)can be demonstrated to be reliable, accurate, and reproducible by the person deploying them; and
(b)take into account the generally recognised state of the art.
See Article 2(18) of the Framework Regulation, as amended by S.I. 2019/539, for the meaning of “designated standard”.