UPDATE: After reading the entry by Misprintt on the SchemaManager and XMLDecoder more thoroughly, I felt the need to tell you all to go check it out! This is a very powerful undocumented feature of Flex (why undocumented?) that could potentially save loads of time on a larger project. Along with the rest of this article, you could automate the parsing of your XML files into bindable model classes with ease.
XML-Schema (.XSD extension) are documents used to describe the format of XML files. They are similar to DTD (Document type declaration) files but much more powerful.
While working on some XML documents for a Flash site, I stumbled across the XML-Schema editor for Eclipse. The editor shows the XSD as a graphical representation of the model that you’re editing that looks similar to a UML class diagram.
Here’s a great article on how it works.