This document describes a simple classification system for coals providing— guidance on the selection of the appropriate ISO standard procedures for the analyses and testing of coals,— international comparison of coals in terms of some key characteristics,— descriptive categorization of coals.The system is applicable to coals of all ranks, but care is required in relation to the classification of some types of coal.The system can be applied to a wide range of representative coal samples, provided their exact nature is stated. Such samples include bore-core seam sections and composite samples, raw (as-mined) coal, washed coal, blends of coals of similar rank and selected, specified size fractions.The system provides a broad framework within which coals can be assessed. The selection of coals for a specific use requires detailed information that enables the likely performance of a coal in a particular application to be anticipated. The wide-ranging list of ISO analyses and test procedures for coals serve this purpose. The selection of the appropriate procedures to be used in assessing a coal depends on the intended use.