Document Structure Description, or DSD, is a schema language for XML, that is, a language for describing valid XML documents.
An example of DSD in its simplest form: This says that element named "foo" in the XML namespace "http://example.com" may have two attributes, named "first" and "second".
It must contain one subelement, named "bar", also in the "http://example.com" namespace.
A "bar" element is not allowed any attributes, character data or subelements.
One XML document that would be valid according to the above DSD would be: This markup language article is a stub.