This document discusses the Biopharmaceutics Classification System (BCS) and its use in determining biowaivers for generic drug products. It outlines the four BCS classes based on a drug's solubility and permeability. Class I drugs are highly soluble and permeable and are eligible for biowaivers if they dissolve rapidly. Class II-IV drugs have additional criteria for biowaivers depending on their class. The document provides detailed definitions and criteria for determining a drug's BCS class and for assessing rapid dissolution to determine if a biowaiver is appropriate.