T e c h n i q u e s a n d C o n t i n u o u s S o f t w a r e E n g i n e e r i n g The notion of abstract data types, developed and formalized already in the 70'ies, is still one of the most important concepts in Computer Science, especially in Theoretical Computer and Software Development Science. In fact, abstract data types have been extended by various parameterization, transformation and modularization concepts which are most important for horizontal and vertical structuring of software systems. More recently abstract data types, mainly used to model static aspects, have been extended by state-oriented and dynamic aspects, leading to the concept of dynamic algebras and dynamic abstract data types. On the other hand the object-oriented paradigm has turned out to be one of the most important concepts for architectural design and programming of all kinds of software systems, especially supported by the commercial success of C++. In fact, there are several formal concepts, like classical and dynamic abstract types, process algebras, co-algebras, actor systems and attributed graph transformations, which have the capability of modelling certain aspects of objectoriented techniques. But it is still open and considered as an important future trend by Horst Reichel, Gerhard Goos and others, to develop a widely accepted formal model for the object-oriented design and programming paradigm. Another important aspect in the area of software engineering, database and information systems as well as communication technology and computer networks is the problem of continuous change of requirements for already existing software systems in all areas of administration, commercial services and industry. This means that today maintenance of software includes re-engineering and hence continuous software engineering. Although this problem is known and faced in practice since the very beginning it has become a matter of research only recently. Unfortunately, formal methods for software development have been almost ne-