Document Type Definition: DTD

• Can be added to specify the allowed structuring:
  • The <exam> element is the root element
  • There can be one or more questions followed by answer pairs
  • Each <question> element is followed by an <answer>
  • The <exam> element has attributes author and paper

If the document references a DTD and matches the DTD, it is called a valid document

All valid documents are well-formed