This document specifies the conditions which need to be taken into consideration in the selection of the type of natural weathering and the natural weathering procedure to be used to determine the resistance of coatings or coating systems (direct weathering or weathering behind window glass). Natural weathering is used to determine the resistance of coatings or coating systems (denoted in the following text simply by coatings) to the sun's radiation and the atmosphere. Special atmospheric influences, e.g. industrial pollution, are not taken into account in this document.