10.—(1) The occupier of any premises where marking occurs must keep any marker—
(a)separately from all other substances; and
(b)except when removed for immediate use, in containers bearing a description of their contents.
(2) At the end of each month, the occupier of any premises where marking occurs must—
(a)take stock of the markers that he stores for use or that are in use at those premises;
(b)make a written record of that stocktake;
(c)preserve that written record for not less than 6 years.