xmlns:atom="http://www.w3.org/2005/Atom"
5. By way of exception to paragraph 4(a), any amount referred to in paragraph 2(c), 3(a) or 3(b) may be expressed as a percentage by weight, unless the amount is less than 0.1% by weight, in which case it shall be expressed in milligrams per kilogram or micrograms per kilogram as appropriate.