RDF allows XML literals to be given as the object node of a predicate. These are written in RDF/XML as content of a property element (not a property attribute) and indicated using the rdf:parseType="Literal" attribute on the containing property element.
<rdf:Description rdf:about="http://example.org/item01">
<ex:prop rdf:parseType="Literal" xmlns:a="http://example.org/a#">
<a:Box required="true">
<a:widget size="10" />
<a:grommit id="23" />
</a:Box>
</ex:prop>
</rdf:Description>
The green part is an XML Literal.