The Study Catalogue is a recommended plan of study. It is intended for the easiest possible course of study. In it you will find a list of compulsory, compulsory options and elective courses, as well as recommendation as to the semester when to enrol in them.
Compulsory courses for your field of study must all be passed in the course of your studies, you must usually choose one out of a few compulsory options per semester (if the Catalogue does not state otherwise), and you choose elective courses by yourselves depending on your interest.
How to search in the Study Catalogue:
Select your mode of study, programme and field of study and you will get to a page with a table including courses. The table is divided by semesters. For each semester it mostly lists compulsory, compulsory options and elective courses. If some courses (e.g. compulsory options) are not listed, they are not offered for your field of study in the given period, so you do not have to worry about them.
Read the instructions in the introductory section of the Catalogue as well as in individual courses!