Abstract. Renovation of buildings is a demanding challenge for computer systems. Nowadays, complex 3D models of historic buildings can be scanned and modelled, including sculptural filigrees and stucco decorations with possibility to generate different projections, cross-sections and elevations according to descriptive geometry rules. However, all of this falls within the field of "3D Modelling". BIM systems work with elements that have to be classified according to their purpose, or according to the way they are realized. The system is then able to sort, filter or group them. Also, it is able to compute their bill of quantity and quality based on their attributes. Last but not least, it has to be able to schematically display civil engineering drawings on the basis of classification of the elements which differ considerably from the display of descriptive geometry. In regular constructions, repeatability and predictability of the links between the elements suit computer systems. Thus, the issue of building renovations in BIM systems is to find a balance between modelling irregular constructions and irregular space arrangements, while maintaining the ability to interact with other BIM elements.

In the paper we indicate the way to allow the coexistence of multiple structures that are mutually supportive, but not mutually exclusive. It allows less organized users to classify entities according to their suitable structure, whilst leaving the possibility for specialised users to classify these entities into related field classification systems or domain ontologies, in mutually beneficial cooperation. Replacing the reductionist enumerative structure with multiplicative categorization should bring organizational and terminological flexibility that will allow future updates without disrupting the existing categorization. It allows one to use parallel hierarchical branches of categories according to aspects and classify the entity into several branches at the same time. It should allow users the freedom to create their own structures without disrupting the structures of other user groups. Such structures could coexist happily side by side. The aim is to indicate the model of an independent data organization system in building design in a multilingual environment, connected through diverse CAD, GIS, BIM, CAFM applications, ECM, CDE, emails, databases and file systems.

In today's organization of data in civil engineering there remains ambiguity, diversity of terminology and consequent lack of clarity. The daily reality is to work with hybrid data sources in a variety of software programs. In CAD programs it is possible to import and convert elements from GIS, but they will be classified only into layers. Or, attach external references from CAD files in BIM, but there still remains the problem of finding your way around the confusing list of layers, and their abbreviations. Also broadly used filesystems as place for store and organise data on disk into files (entities) and hierarchical structure of folders (categories) is limited by reductionist categorization approach. Another problem shows with absence of multilingual approach. The limits are in the methods of data organization, and so only partially portable. Therefore, if there is a common denominator to all problems, it is the absence of a unifying organizational environment. In current computer applications used in civil engineering, methods of data classification are implemented that do not allow multiplicative or faceted categorization and thus inevitably create an antagonistic environment with any previous or future classification system. Unfortunately, even if a software tool implements a modern multiplicative categorization or domain ontology, it will not significantly solve the overall situation, because it will still not be possible to use such a method of categorization in other applications. Therefore, if there should exist a solution that would significantly facilitate cooperation and orientation in the data, it must inevitably work independently, across diverse software applications, with the ability to link the functions of the application with such a separate categorization system.