10. This Part of these Regulations shall apply as respects the use for trade (other than for the purpose of marking weighing or measuring equipment) of abbreviations of, or symbols for, units of measurement.
11.—(1) Only those symbols or abbreviations set out in Column 2 of Schedule 3 to these Regulations may be used for trade to indicate the relevant unit of measurement set out in Column 1 of that Schedule.
(2) In the case only of an abbreviation of an imperial unit so set out, the letter "s' may be added to it, when appropriate, to indicate the plural.