Clarity regarding controlled vocabularies, taxonomies, thesauri, ontologies, and metamodels. With all the scuttlebut going around about folksonomies and tagging, these are important terms to understand. In the process of tagging, it's pretty noticeable
J. Curran, und M. Moens. Proceedings of the ACL-02 workshop on Unsupervised lexical acquisition - Volume 9, Seite 59--66. Morristown, NJ, USA, Association for Computational Linguistics, (2002)