Example
<?xml version="1.0"?>
<!DOCTYPE items [
<!ELEMENT items (item*)>
<!ELEMENT item (product, quantity)>
<!ELEMENT product (description, price)>
<!ELEMENT quantity (#PCDATA)>
<!ELEMENT description (#PCDATA)>
<!ELEMENT price (#PCDATA)>
]>
<items>
<item>
<product>
<description>Ink Jet Refill Kit</description>
<price>29.95</price>
</product>
<quantity>8</quantity>
</item>
<item>
<product>
<description>4-port Mini Hub</description>
<price>19.95</price>
</product>
<quantity>4</quantity>
</item>
</items>