per cent

Where the standards of strength, weight or quantity, as the case may be, of any ingredient or component part of any food are mentioned on the label, unless otherwise provided in these Regulations, "per cent" shall mean per cent by weight, "parts per million" shall means parts per million by weight, and "parts per billion" shall mean part per billion by weight.
PU(A) 437/2011 - FOOD REGULATIONS 1985
15. Statement of strength of ingredient.

per cent

Where the standards of strength, weight or quantity, as the case may be, of any ingredient or component part of any food are mentioned on the label, unless otherwise provided in these Regulations, "per cent" shall mean per cent by weight, "parts per million" shall means parts per million by weight, and "parts per billion" shall mean part per billion by weight.
PU(A) 437/1985 - FOOD REGULATIONS 1985
15. Statement of strength of ingredient.