The traditional notion of the curriculum as a fixed list of topics to be studied sequentially is under strain as pressure for flexibility in education increases. However, curriculum flexibility can lead to curriculum complexity, hindering learners in the development of their competences. This article presents a formal model for the description of curricula, designed to underpin guidance support systems for learners. The article compares the model to other work in the area, illustrates its application with a number of case studies and concludes with a discussion of the broader e-learning infrastructure required in implementing the approach.