Gleaning Resource Descriptions from Dialects of Languages (GRDDL) versus
RDF in XHTML (the name it had earlier this year). Now which would a slightly advanced author (one who has a basic grasp of RDF and knows how the write a valid XHTML document) understand better?
Ah, finally. I [among others] have developed a similar concept, which uses the Schema of a given XML Document to automaticalle generate Topic Maps from that. We used the apps-info-elemtent within the documentation element of an element-definition, to declare, which content of which elements of an XML-Document should be Transformed into Topics and Associations.
You simply write an XSLT-Script, that takes the Schema, as XML-Document, and throws out another XSLT-Script, which you use with your XML-Data, to generate a Topic Map. We used it with Bibliographies, they are almost perfect for that.
What's the use? (And why create your own markup language when so many formats are available?)