XPS, or the XML Paper Specification, is a (relatively) new document format developed by Microsoft.  XPS is analogous to PDF; both are fixed document formats designed to be platform-independent.  Being fixed, the layout of the document is set at design time and, hypothetically, should remain the same no matter what device produces the document.  While PDFs are based on PostScript, an ancient and crusty language used to plot mammoths and gazelle on cave walls, XPS documents are described using XAML, a superset of the hyper-modern and streamlined (that's why everything is surrounded with < >'s--to keep down on wind resistance) XML.

The primary benefit of describing XPS documents in XAML is that XAML maps directly to objects, their properties and events.  This means that there is a built in document object model (DOM) that can be used to create, load, parse, modify and save XPS documents in memory at runtime.

One of the biggest problems facing developers when trying to learn how to use XPS documents is that the current documentation on MSDN about XPS documents is utter crap.  Hopefully, it will get better.  But until then...

Up next, a quick overview of the DOM, and creating XPS documents in memory.