Waterflow classification of malnutrition in children takes into account?

Waterlow&;s classification of PEM: It defines two groups- 1. Malnutrition with a retarded growth, in which a drop in height/age ratio points to a chronic condition - shoness/stunting. It is an index of the duration of malnutrition 2. Malnutrition with a low weight for a normal height, in which the weight for height ratio is indicative of an acute condition of rapid weight loss/ wasting. It is an index of severity of malnutrition. Reference: GHAI Essential pediatrics, eighth edition