Like schemas, transforms are XML files, and they must conform to the rules for well-formed XML. Transforms can also be extremely complex, and writing them is a job for professionals. Again, however, it will help you get the results you want if you know enough about transforms to help in planning them. The illustration shows part of a transform that writes data from the <CAT> file, discussed in previous lessons, into a table on a Web page.
This example shows just one way to write a transform. A transform used to convert data into a document or a diagram would contain tags specific to the program and the display context.
In case you were wondering, Extensible Style Sheet Language isn't a language separate from XML. It's a vocabulary of XML. A transform is just another XML document.