SUMMARYFeatures are an established means of adding non-geometric information and extra geometric semantics to conventional CAD systems. It has been already realised that although feature-based modelling is necessary for the next generation of integrated design and manufacturing systems, inherent feature interactions pose a difficulty in representing and manipulating geometric design. This paper presents a structured multi-level geometric feature interaction classification scheme implemented within a Design-by Feature (DbF) system for representation validation analysis. Various feature interaction definitions and classification methods are first surveyed. The elements and the tests used for the identification process are presented. The classification encompasses existing feature interference cases found in the literature, uses a clear structure for the classification and, is applied at three different levels.