Abstract. This tutorial describes the rationale for and use of an ontology for extensive semantic interrelation of documents to increase "sustainable development", i.e. continuous long-term usability of the contents. The ontology is structured via Packages (corresponding to whole documents); these may be imported such that semantic interrelation becomes possible not only within a document but also between different documents. Coherence and consistency are enhanced by change management in a Repository, including version control and configuration management. The LATEX commands for the declaration and definition of classes, objects and relations, and References to them, are described in detail, such that these can be used in standard LATEX documents. Moreover, structuring via Packages is introduced and the benefits of change management in a Repository are explained.