BizTalk Server 2000 uses XML at its core, but as you can see, regardless of the file format the definition of the document structure is a snap. In the next chapter, you will learn how to use a BizTalk specification to map one specification to another. In other words, how to take a document generated using Fidelity's positional flat file format and transform it into the XML format that Sunset Bank's internal systems are designed to process.