In this paper, we propose a method for structuring a competency repository based on 5 principles. Two of them consist in using a composition relation to define competencies at several levels of abstraction and a prerequisite relation to establish prerequisites between competencies. To illustrate the contributions of these principles, an application in the domain of information systems design and implementation is fully developed. This application is based on the discussions that were carried out within the "Competency Working Group" of the French network of MIAGE (Méthodes Informatiques Appliquées à la Gestion des Entreprises) Masters and within the framework of the IDEFI-N OPENMIAGE project funded by the French ANR (Agence Nationale de la Recherche). The proposed repository, in addition to a new structure, incorporates new competencies compared to existing repositories, in particular with regard to strategic management of the IS, development techniques, interpersonal competencies, prerequisites coming from basic disciplines. This repository aims primarily to help the organization of academic and professional training and to allow the assessment of personal skills.