16.—(1) Barley, oats, wheat (including durum wheat and spelt wheat) or naked oats classified as basic seed, or certified seed of categories C1 or C2, may be marketed as being of a higher voluntary standard, which is a standard higher than that regulated under Chapter 1, if it meets the higher standards in this Chapter.
(2) The crop must have at least 99.99% (by number) species purity.
(3) Other than a hybrid, the minimum varietal purity of seed is—
(a)99.95% for basic seed;
(b)99.9% for C1 seed;
(c)99.7% for C2 seed.
(4) In the case of C1 and C2 the seed must have 99% by weight analytical purity.