I thought your article was simplified and made easy reading. Hiowever, you did miss out on some of the limitations of xml.

The main limitation being that xml cannot handle relational data or multiple children.

You cannot stored relational data in a xml format. If you want to query acroess a relational set, you need to bring xml into a table or equivalent to be able to do so.

Secondly, and I think more importantly, the issue of multiple children. If you have more than one child, xml will not allow you store it. Take for example a company organisational hierarchy. At the root you would have CEO for instance. Then if you have 5 people underneath, all the same level you get the problem of having to tag them all together. Then you cannot go down any more paths with the 5 people tagged together.

XML can only handle one single record all with single values, in the manner that you gave in your sample. What would happen if you had 2 authors. You would need another line like <FNAME>Surname2</FNAME> and the xml would not parse without errors.

Oh, almost forgot. Cannot use characters likle ampersand in xml document or it will not parse.