This chapter has covered quite a bit of ground as far as how SQL and XML interact, including the storage, validation, modification, and generation of XML documents, yet it has barely scratched the surface as far as XML is concerned. There is much more to XML than has been demonstrated here, and far more to XML Schema than was utilized in the schema definition for the purchase order documents. Additionally, there are a large number of related technologies, such as Document Object Model (DOM) and Extensible Stylesheet Language Transformations (XSLT), that have not been covered in this chapter, but which are available in Oracle XML DB. It is impossible to cover all of this territory in a single chapter, so we urge you to utilize the resources mentioned earlier in the chapter if you are new to XML.