In addition to Bob's reference here is an address for those who -as I- consider themselves as newbies in XML Schema.
Visit and learn the basics. There are also links to the main web-related technologies.

>Hi All,
>
>I've been using the old XDR schemas for quite a while now, waiting for W3C to release the XML schema spec. It was released this week so I decided it was time to take a look. WOW!
>
>If you're into OO stuff, you will love it. My hat's off to the W3C Working Group that did this work. They have moved creating custom data types to a fine art. You can define patterns (like (###) ###-#### or a template for a valid IP address), create abstract data types, and set value ranges, just to name a few features.
>
>I followed a link from the W3C site, http://www.xfront.com , and found an excellent tutorial. If you're the least bit interested in learning the current schema spec, this is a great tool.

Solo se que nada se

Fausto J. Garcia Pino - MCSD.NET
.NET, Oracle, Tronador & Fondismo!