A Comparison of (Semantic) Markup Languages

Several languages have been proposed as candidates for semantic markup. We needed to adopt a language for our current research on developing user-oriented tools operating over the Semantic Web. This paper presents the results of our analysis of three candidates that we considered: XML, RDF, and DAML+OIL along with their associated schemas and ontology specifications. The analysis focuses on the expressiveness of each language, and is presented along several dimensions and summarized in a comparison table. A surprising result of our analysis is the decision to adopt XML(Schema) for practical reasons, since it is able to accommodate a relatively expressive set of constructs and is widely known and commercially supported. We also discuss how we plan to complement XML(S) with a small set of conventions, so that we will have an easier transition to other markup languages in the future