RDF and Topic Maps may appear to address this problem (they are after all specifications for expressing “semantic relations,” and they both have XML transfer syntaxes), but in reality their focus is on generic semantics — propositions about the real world — and not the semantics of markup languages.
TEI By Example offers a series of freely available online tutorials walking individuals through the different stages in marking up a document in TEI (Text Encoding Initiative). Besides a general introduction to text encoding, step-by-step tutorial modules provide example-based introductions to eight different aspects of electronic text markup for the humanities. Each tutorial module is accompanied with a dedicated examples section, illustrating actual TEI encoding practise with real-life examples. The theory of the tutorial modules can be tested in interactive tests and exercises.
As I see it, TEI is for describing the elements of a document; transforming to HTML with RDFa can add a meaningful interpretative layer, stating what the document is saying about the external world.
TEI is XML based, and thus it suffers heavy limitations, such as overlapping annotations. RDF is able to overcome this, using ontology vocabularies and allowing powerful queries.
En RDF, la logique structurelle est toujours la même, puisqu'elle est intrinsèque au modèle : <Sujet> <Prédicat> <Objet>. La validation « structurelle » de RDF se situe donc au niveau de l'assertion ou de la donnée à la différence de XML dont la validation est documentaire. En réalité, RDF ne s'intéresse pas à l'encodage d'une structure, mais plutôt à celui de la logique des données. C'est là que rentrent en jeu les ontologies.
Currently, the SIG is working on a document called Guidelines for the creation of TEI documents that will map well to ontologies such as the CIDOC-CRM.
T. Nellhaus. 1, page 257-277. (2001)"It is unclear, however, what relationship there might be between TEI headers and RDF. In principle, it should be feasible to create a crosswalk...".