The main aim in this Master thesis is to analyse how an ideological view may have influenced the shape of hierarchies with a specific concentration on the concept of fiction genre in the latest versions of the systems SAB and DDC. Our thesis is that no theoretical classification scheme can be recognized as objective. With an ideological/institutional perspective we look at the structures behind these systems. As a vehicle we use the hermeneutic circle to show the play between part and unit by focusing and analysing three different levels: the content level the concept level the ideological level. The first level is in the shape of a historical background and an analysis of concept with focus on content. The second level is the concept level and Henriksens structural model is used as a point of departure for an investigation of which fiction genres has been implemented in respectively system and how these concepts are treated according to the models four planes. At the last level we try to uncover ideological structures in the systems. Finally we put the pieces together in a comparative study. To sum up we use four different methods that is, analysis of concept, Henriksens structural model, hermeneutic and a comparative study each in combination with at least one of the three levels. The results of the empirical study are to some degree visualised with diagrams or other illustrations and the outcome of the comparative analysis are as far as possible in form of tables and other alternatives. From these results conclusions have been drawn of which a few will be outlined here. At the concept level one of the conclusions is that genres in SAB are divided according to extent while genres in DDC are divided after type of principle of division. At the content level the conclusion shows that the concept of genre is no element you can neglect because of the many meanings that different disciplines put into the word from pure form aspects to demands of power. The ideological level involves the three forms of nature that is epic, lyric and drama. The point is that these three forms of nature still are at the top of the genre hierarchy when it comes to fiction in both the systems. A view that indicates the roots back to ancient Greece and a patriarchal view in combination with an idealistic way of looking at the world.