• To validate the XML document, you will need to add DTD rules to describe

  the following structure.

  • Add a rule specifying the

    name

    element, whose contents

    should be character data.

  • Modify the rule for the

    menuitem

    element, so that its

    contents begins with a

    name

    element.

  • Add a rule specifying the

    item

    element, which should be an

    empty element.

  • Add a rule specifying the

    ingredients

    element; its contents

    should be zero or more occurrences of the

    item

    element.

  • Modify the rule for the

    menu

    element, so that its contents

    requires an

    ingredients

    element, before zero or more

    occurrences of the

    service

    element.

  • Modify the rule specifying the attributes of the

    item

    element, to add the

    id

    attribute; this should be of type

    ID

    , and it is required.

  • Add a rule specifying that the

    service

    element should have

    an attribute called

    name

    ; its value must be one of

    breakfast, lunch, or dinner

    and

    it is a required attribute.

  • Lastly, write a rule specifying the

    ref

    and

    amount attributes of the ingredient

    element.

    The

    ref

    attribute is required, and it should be of type

    IDREF

    : this means that the value of this attribute must

    refer to the value of an

    ID

    type attribute somewhere in the

    XML document.

    The value of the

    amount

    attribute is allowed to be an

    arbitrary string, and it should have a default value of

    1.0

    .

• Now try to validate the document again using the

  xmllint

  tool.

  You will find that there are two more errors.

  Fix these errors, by making one change in the XML code.

Once you have written all the ncessary DTD schema rules, and the XML validates, enter your final DTD schema in to the box below, or upload it as a separate file.