"[T]he average company’s enterprise system - i.e. the overall system of IT related entities - is today highly complex. Technically, large organizations possess hundreds or thousands of extensively interconnected and heterogeneous single IT systems performing tasks that varies from enterprise resource planning to real-time control and monitoring of industrial processes. Moreover are these systems storing a wide variety of sometimes redundant data, and typically they are deployed on several different platforms... Organizationally, the enterprise system embraces business processes and business units using as well as maintaining and acquiring the IT systems. The interplay between the organization and the IT systems are further determined by for instance business goals, ownership and governance structures, strategies, individual system users, documentation, and cost. Lately, Enterprise Architecture (EA) has evolved with the mission to take a holistic approach to managing the above depicted enterprise system. The discipline’s presumption is that architectural models are the key to succeed in understanding and administrating enterprise systems. Compared to many other engineering disciplines, EA is quite immature in many respects. This thesis identifies.. firstly, the lack of explicit purpose for architectural models... [A] company’s Chief Information Officer (CIO) should guide the rationale behind the development of EA models. In particular, distribution of IT related information and knowledge throughout the organization is emphasized as an important concern uncared for. Secondly, the lack of architectural theory is recognized..."