Product Data Technology encompasses the information related to all stages in the product life cycle from product design via production planning, production processes, production control etc. through the delivery and operational stages of the technical product. Product Data Technology takes a coherent, unified view of the information captured in this whole life cycle and provides methodologies to support this integrated perspective. The Product Data Technology Advisory Group (PDTAG), a Special Interest Group of the CIME Division of the Commission of the European Communities founded in 1991, has encouraged the formation of a new subseries on Product Data Technology within the existing series of Research Reports ESPRIT. This subseries will provide a depository for the important contributions made by ESPRIT projects to the evolving area of Product Data Technology, particularly also those based on STEP (ISO 10303). PDTAG is grateful to Springer Publishers for establishing this subseries which will serve to report recent international developments in Product Data Technology. The current volume describes the results of the ESPRIT Project CACID (Proj. No. 5168), dealing with the subject of computer-aided concurrent integral design. Concurrent engineering provides an important enhancement of computer-aided product design by offering a framework and methodology for the management of design projects with multiple parallel tasks. Concurrent Engineering is one of the important growth areas for Product Data Technology.