Gruber said he saw four different ways of adding meta-tags to material, ranging from the loosest to the most strict:
1.Folksonomy (informal, user-defined)
2.Controlled vocabularies (the user must deploy a set of defined terms)
3.Taxonomy (Pre-defined terms in which specific terms are subsets of more general terms)
4.Ontology (A rich set of relationships is mapped out among all the terms)
F. Suchanek, G. Kasneci, и G. Weikum. Proceedings of the 16th international conference on World Wide Web, стр. 697--706. New York, NY, USA, ACM, (2007)
F. Suchanek, G. Kasneci, и G. Weikum. Proceedings of the 16th International Conference on World Wide Web, стр. 697--706. New York, NY, USA, ACM, (2007)