Some knowledge of XML, XSLT, and XPath is required, so read some tutorials if necessary.

Selecting a structure for your data in XML is completely arbitrary. You can represent the same data in several different ways. Below is XML that represents the same data four different ways. The XML represents a Census record. A Census record has a country, a year, a small size, and a large size. This information can be represented by elements or elements and attributes.

TYPE1 uses attributes and makes a very small footprint.

TYPE2 uses only elements and because of formatting for readability it uses a little more screen real estate.

TYPE3 and TYPE4 use a combination of elements and attributes.

<?xml version="1.0" encoding="utf-8" ?>
<STUFF>
   <TYPE1>
      <CENSUS COUNTRY="USA" YEAR="1930">
         <PAGE SIZE="SMALL">17x11</PAGE>
         <PAGE SIZE="LARGE">27x19</PAGE>
      </CENSUS>

      <CENSUS COUNTRY="USA" YEAR="1880">
         <PAGE SIZE="SMALL">17x11</PAGE>
         <PAGE SIZE="LARGE">19x25</PAGE>
      </CENSUS>

      <CENSUS COUNTRY="UK" YEAR="1871">
         <PAGE SIZE="SMALL">9.5x15</PAGE>
         <PAGE SIZE="LARGE">9.5x15</PAGE>
      </CENSUS>

      <CENSUS COUNTRY="UK" YEAR="1891">
         <PAGE SIZE="SMALL">11x16</PAGE>
         <PAGE SIZE="LARGE">11x16</PAGE>
      </CENSUS>
   </TYPE1>

   <!-- **************************************************** -->

   <TYPE2>
      <CENSUS>
         <COUNTRY>USA</COUNTRY>
         <YEAR>1930</YEAR>
         <PAGE>
            <SIZE>
               <SMALL>17x11</SMALL>
               <LARGE>27x19</LARGE>
            </SIZE>
         </PAGE>
      </CENSUS>

      <CENSUS>
         <COUNTRY>USA</COUNTRY>
         <YEAR>1880</YEAR>
         <PAGE>
            <SIZE>
               <SMALL>17x11</SMALL>
               <LARGE>19x25</LARGE>
            </SIZE>
         </PAGE>
      </CENSUS>

      <CENSUS>
         <COUNTRY>UK</COUNTRY>
         <YEAR>1871</YEAR>
         <PAGE>
            <SIZE>
               <SMALL>9.5x15</SMALL>
               <LARGE>9.5x15</LARGE>
            </SIZE>
         </PAGE>
      </CENSUS>

      <CENSUS>
         <COUNTRY>UK</COUNTRY>
         <YEAR>1891</YEAR>
         <PAGE>
            <SIZE>
               <SMALL>11x16</SMALL>
               <LARGE>11x16</LARGE>
            </SIZE>
         </PAGE>
      </CENSUS>
   </TYPE2>

   <!-- **************************************************** -->

   <TYPE3>
      <CENSUS>
         <USA YEAR="1930">
            <PAGE SIZE="SMALL">17x11</PAGE>
            <PAGE SIZE="LARGE">27x19</PAGE>
         </USA>

         <USA YEAR="1880">
            <PAGE SIZE="SMALL">17x11</PAGE>
            <PAGE SIZE="LARGE">19x25</PAGE>
         </USA>

         <UK YEAR="1871">
            <PAGE SIZE="SMALL">9.5x15</PAGE>
            <PAGE SIZE="LARGE">9.5x15</PAGE>
         </UK>

         <UK YEAR="1891">
            <PAGE SIZE="SMALL">11x16</PAGE>
            <PAGE SIZE="LARGE">11x16</PAGE>
         </UK>
      </CENSUS>
   </TYPE3>

   <!-- **************************************************** -->

   <TYPE4>
      <CENSUS>
         <COUNTRY>
            USA
            <YEAR>
               1930
               <PAGE>
                  <SIZE TYPE="SMALL">17x11</SIZE>
                  <SIZE TYPE="LARGE">27x19</SIZE>
               </PAGE>
            </YEAR>
            <YEAR>
               1880
               <PAGE>
                  <SIZE TYPE="SMALL">17x11</SIZE>
                  <SIZE TYPE="LARGE">19x25</SIZE>
               </PAGE>
            </YEAR>
         </COUNTRY>
         <COUNTRY>
            UK
            <YEAR>
               1871
               <PAGE>
                  <SIZE TYPE="SMALL">9.5x15</SIZE>
                  <SIZE TYPE="LARGE">9.5x15</SIZE>
               </PAGE>
            </YEAR>
            <YEAR>
               1891
               <PAGE>
                  <SIZE TYPE="SMALL">11x16</SIZE>
                  <SIZE TYPE="LARGE">11x16</SIZE>
               </PAGE>
            </YEAR>
         </COUNTRY>

      </CENSUS>
   </TYPE4>
</STUFF>

Often, an XML document needs to be converted to a new structure. That is where XSLT comes in. There are lots of good tutorials on XSLT. I found that there weren't very many examples that covered more than a few aspects of XSLT. Thus, I decided to write an XSLT for each type in my XML document. So, I wrote some XSLT to convert each type into all of the other types. Some things I had to overcome were converting attributes into elements, element values into attributes, selecting nodes back up the tree (the parent in my case), stripping off white space, and adding white space.

About the Author
MS/CS. .NET, J2EE, C++, Tibco Rendezvous, MFC, OS X, XML, XSLT. Interests: 2D/3D/ND Computer Graphics, Messaging, Webservices, Software Process. Real name: Geoffrey Slinker http://home.att.net/~geoffrey.slinker/agile.html