Indicate that an unprefixed element and all its unprefixed descendant 
elements belong to a particular namespace by attaching an xmlns 
attribute with no prefix:
<DATASCHEMA xmlns="http://www.w3.org/2000/P3Pv1">
  <DATA name="vehicle.make" type="text" short="Make" 
        category="preference" size="31"/>
  <DATA name="vehicle.model" type="text" short="Model" 
        category="preference" size="31"/>
  <DATA name="vehicle.year" type="number" short="Year" 
        category="preference" size="4"/>
  <DATA name="vehicle.license.state." type="postal." short="State" 
        category="preference" size="2"/>
  <DATA name="vehicle.license.number" type="text" 
        short="License Plate Number" category="preference" size="12"/>
</DATASCHEMA>
Both the DATASCHEMA and DATA elements are in the 
http://www.w3.org/2000/P3Pv1 namespace. 
 Default namespaces apply only to elements, not to attributes. 
Thus in the above example the name, type, short, category, and size attributes are not in any namespace. 
You can change the default namespace within a particular 
element by adding an xmlns attribute to the element. 
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:xlink="http://www.w3.org/XML/XLink/0.9">
  <head><title>Three Namespaces</title></head>
  <body>
    <h1 align="center">An Ellipse and a Rectangle</h1>
    <svg xmlns="http://www.w3.org/Graphics/SVG/SVG-19991203.dtd" 
         width="12cm" height="10cm">
      <ellipse rx="110" ry="130" />
      <rect x="4cm" y="1cm" width="3cm" height="6cm" />
    </svg>
    <p xlink:type="simple" xlink:href="ellipses.html">
      More about ellipses
    </p>
    <p xlink:type="simple" xlink:href="rectangles.html">
      More about rectangles
    </p>
    <hr/>
    <p>Last Modified February 13, 2000</p>    
  </body>
</html>