15.—(1) Forest reproductive material in respect of which a Master Certificate has been obtained pursuant to these Regulations may be mixed during production to create a single lot in one of the ways described in paragraphs (3) and (4).
(2) A single lot of mixed forest reproductive material created in accordance with paragraph (1) shall be distinguished as a lot by reference to the identification criteria provided for in regulation 14(1)(a) to (k).
(3) Forest reproductive material may be mixed where it is derived from two or more units of approval within a single region of provenance and where the units of approval each fall within one of the categories “source-identified” or “selected”.
(4) Forest reproductive material of different years of ripening may be mixed where the material is derived from a single unit of approval.