The DTD for the markup language of

the previous example

  <?xml version="1.0" encoding="ISO-8859-1"?>

  <!ELEMENT recipebook (recipe)+ >

  <!ELEMENT recipe (recipetype, title, ingredient+, step+) >

  <!ELEMENT title (#PCDATA) >

  <!ELEMENT ingredient (#PCDATA) >

  <!ELEMENT step (#PCDATA) >
  <!ATTLIST step number CDATA #REQUIRED >

  <!ELEMENT recipetype EMPTY >
  <!ATTLIST recipetype name CDATA #REQUIRED >