Reiner Anderl The Advanced Modelling part of the CAD*I project aimed at the development of a new generation of modelling techniques as a basic functionality of future CAD/CAM systems. The methodology and concepts for advanced modelling techniques, their availability in the communication interface of a CAD/CAM system and their influence on internal interfaces in the software architecture of a CAD/CAM system are fundamental results of advanced modelling work. These results form the basis for the development of a new generation of CAD/CAM systems which are called product modelling systems. CAD/CAM systems today mainly support the geometric description of a technical part or its description as a technical drawing. Advanced geometric modelling capabilities deal with parametric design functions embedded into CAD/CAM systems. However, development strategies for future CAD/CAM systems are directed toward the following: 1. The development of product modelling systems and 2. the development of integrated systems based on CAD, CAP (Computer Aided Planning), CAM and other CIM (Computer Integrated Manu facturing) functionalities. This volume presents the results of research work performed within ESPRIT Project 322 "CAD Interfaces (CAD I)". It describes the concept for a methodology and guidelines to extend geometric modelling systems by modelling functions for the design of technical products. These functions are based on providing more semantics and design operations. A two-level concept for extending geometric modelling functions is presented: geometric associative functions and technical functions reflecting technical terms and technical form features are defined. For the implementation of an advanced modelling system, a specification for procedural interfaces and the description of a user interface are given as typical examples. Dieser ESPRIT-Bericht beschreibt ein Konzept zur Erweiterung von Funktionen der Geometrischen Modellierung auf technische Anwendungen. Es wird ein Stufenkonzept vorgestellt, das aufbauend auf geometrischen Funktionen zunächst geometrisch-assoziative und sodann technische Funktionen spezifiziert.