GRDDL is a mechanism for Gleaning Resource
Descriptions from Dialects of Languages. The
GRDDL specification introduces markup for declaring that an XML
document includes gleanable data and for linking to an algorithm,
typically represented in XSLT, for gleaning the RDF data from the
document.The markup includes a namespace-qualified attribute for use in
general-purpose XML documents and a profile-qualified link
relationship for use in valid XHTML documents. The GRDDL mechanism
also allows an XML namespace document (or XHTML profile document)
to declare that every document associated with that namespace (or
profile) includes gleanable data and for linking to an algorithm
for gleaning the data.A corresponding GRDDL specification
provides complete technical details. A GRDDL Primer demonstrates
the mechanism on XHTML documents which include widely-deployed
dialects, more recently known as microformats.