Chapter 47 - NOTE 1. For the purposes of heading No. 47.02, the expression "chemical wood pulp, dissolving grades" means chemical wood pulp having by weight an insoluble fraction of 92% or more for soda or sulphate wood pulp or of 88% or more for sulphite wood pulp after one hour in a caustic soda solution containing 18% sodium hydroxide (NaOH) at 20oC, and for sulphite wood pulp an ash content that does not exceed 0.15% by weight.