Architects extensively use graphic representations to communicate their design ideas personally, between professionals, and others. The design drawing therefore, is an important medium if we want to establish design support by means of computers. In order to make drawings accessible for computers, it is necessary to understand how design drawings are carriers of knowledge. In this text we outline our research on this question. We investigate how graphic representations are structured, what these structures are, what their knowledge content is, and how they can be applied in Computer Aided Architectural Design as intelligent drawing tools.