Modelling of information is necessary in developing information systems. Information is acquired from many sources, by using various methods and tools. It must be recognized, conceptualized, and conceptually organized efficiently so that users can easily understand and use it. Modelling is needed to understand, explain, organize, predict, and reason on information. It also helps to master the role and functions of components of information systems. Modelling can be performed with many different purposes in mind, at different levels, and by using different notions and different background theories. It can be made by emphasizing users' conceptual understanding of information on a domain level, on an algorithmic level, or on representation levels. On each level, the objects and structures used on them are different, and different rules govern the behavior on them. Therefore the notions, rules, theories, languages, and methods for modelling on different levels are also different. It will be useful if we can develop theories and methodologies for modelling, to be used in different situations, because databases, knowledge bases, and repositories in knowledge management systems, developed on the basis of models and used to technically store information, are growing day by day. In this publication, the interest is focused on modelling of information, and one of the central topics is modelling of time. Scientific and technical papers of high quality are brought together in this book.

This volume contains the best papers presented at the 12th East-European Conference on Advances in Databases and Information Systems (ADBIS 2008) held during S- tember 5-9, 2008, in Pori, Finland. The series of ADBIS conferences is the successor of the annual international workshops with the same title that during 1993-1996 were organized in Russia by the Moscow ACM SIGMOD Chapter. ADBIS 2008 continues the series of ADBIS conferences held in St. Petersburg, Russia (1997), Poznan, Poland (1998), Maribor, Slovenia (1999), Prague, Czech Republic (2000), Vilnius, Lithuania (2001), Bratislava, Slovakia (2002), Dresden, Germany (2003), Budapest, Hungary (2004), Tallinn, Estonia (2005), Thessaloniki, Greece (2006), and Varna, Bulgaria (2007). The conferences are initiated and supervised by an international Steering Committee chaired by professor Leonid Kalinichenko. The ADBIS conferences established an outstanding reputation as a scientific event of high quality serving as an internationally highly visible showcase for research achie- ments in the field of databases and information systems. ADBIS 2008 aimed to create conditions for experienced researchers to impart their knowledge and experience to the young researchers at pre- or post-doctoral level, and to promote interaction and colla- ration between European research communities (especially from Central and East Europe) and the rest of the world. The conference encourages contacts between the p- ticipants who are nationals of, but active outside, the Member States and Associated States and their colleagues in Member States and Associated States. Special attention is paid to collaboration of researchers in Central and East Europe.