Just as you could probably see the power and reasoning behind DTDs, I hope that you can appreciate that XML Schema documents are that much more powerful. Their power comes in their incredible flexibility. This chapter took a look at the principles you need to build XML Schema documents and focused on building elements, attributes, and more. You will find that schema documents are a big part of most XML technologies-whether you are working with Web services, RSS feeds, or others.
The next chapter looks at another schema technology that is quite flexible as well, but is fairly new on the scene-RELAX-NG.