The traditional notion of the curriculum as a fixed list of topics to be studied sequentially is under strain as the pressure for flexibility in education increases. However, curriculum flexibility can lead to curriculum complexity, so that guidance systems are needed to assist learners in their study choices. This article proposes the use of the open, technical specification IMS Learning Design as a formal model for the description of curricula used by guidance support systems for learners. The article compares the approach to other work in the area, and illustrates its application with a number of case studies. The article concludes by describing the type of advanced guidance services which are enabled through a standardized approach and examining the e-learning infrastructure required when implementing the approach.