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A Gentle Introduction to xml

Using entities

We have a simplification of the xhtml specification.

Rules to be enforced

The body tag can contain block elements such as p or div
The block elements p and div can contain Inline elements.
The inline elements can be PCDATA and bold and italics.
We want to allow b and i nodes to be nested to an arbitrary depth

Change the dtd so that the xml on the left passes validation and the xml on the right fails validation.

Valid	Invalid
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> <p>one <b>two</b></p> <div>three <i>four</i></div> </body>	<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> <div><p>x</p></div> </body>
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> <p>one <b>two</b></p> </body>	<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> one <i>two</i> </body>
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> <p>one <b>two <i>three</i></b></p> <div>four <b>four <b>five</b></b></div> </body>	<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE body SYSTEM "body.dtd"> <body> <p><p/></p> </body>

Valid

Invalid

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
  <p>one <b>two</b></p>
  <div>three <i>four</i></div>
</body>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
 <div><p>x</p></div>
</body>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
  <p>one <b>two</b></p>
</body>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
 one <i>two</i>
</body>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
  <p>one <b>two <i>three</i></b></p>
  <div>four <b>four <b>five</b></b></div>
</body>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE body SYSTEM "body.dtd">
<body>
  <p><p/></p>
</body>