This paper proposes an approach to multiple-viewpoint design modelling based on the concept of semantic markup of digital models of a design. The core of the concept is to make the engineering significance (semantics) of entities in a model of an artefact explicit through markup of the same model by engineers from multiple disciplines. Such markup, combined with current technologies that allow the computer interpretable specification of meaning and executable specifications of process, should allow a higher degree of automation of the manipulation of models within the design process, reducing the amount of user effort required. The development of the approach from concepts drawn from feature technologies and the Semantic Web is described along with experimental work carried out in a current generation commercial Computer-Aided Engineering (CAE) suite to test the feasibility of a structured markup for CAE models. The paper discusses the form that a fully realised semantic markup-based CAE system may take. Key elements of such a system are identified and the paper ends with a description of the planned development of the approach.