Abstract: The invention relates to a data processing device, a method and a computer programme for computer-aided substation tendering. Conventional substation tenders rely on by-hand selection of components representing not-preengineered, not-reusable substation parts. Such tenders are inaccurate and time-consuming. In this disclosure a module (2) represents a reusable preengineered substation part and is indexed according to an intuitive multiple-index categorisation system (12), has a standardized name (14) for designating all its related files and for encoding its function in an intuitively understandable, and has a module-descriptor (3) providing standardised information (4-10) to application routines for cost calculation (1a), technical data accumulation (1d), graphics accumulation (1b) and tender text accumulation (1c).