VTT Information Technology in association with Valmet Corporation, the world's leading manufacturer of paper and paper finishing machinery carried out the research project ''Document Management by Product Models''. The aim of the project was to design a prototype system for the production of customer documentation based on a product model by integrating the components in the production of technical documentation with a delivery-related product model. The customer documentation model is achieved with from the structured information modelling techniques introduced in the SGML standard. The product modelling solution is an object-based approach to implementing STEP constructions. A practical, graphics-based prototype tool is developed for managing product structures in a close relationship with SGML documentation.