An XML-based document format from Microsoft. Providing full page layout capabilities, XML Paper Specification (XPS) also allows digital signatures and digital rights to be applied to the documents. Like Adobe's PDF technology, XPS enables a page design to be maintained intact from computer to computer regardless of the fonts that reside in the target computer (see PDF). The XPS viewer application (the XPS counterpart to Adobe Acrobat Reader) is included in Windows, starting with Vista. It renders XPS documents in an Internet Explorer window that contains additional options for navigating the document. XPS is a subset of the Extensible Application Markup Language (XAML), which is used to define elements in the Windows user interface (see XAML). An XPS Package - Parts and Relationships XPS defines a data container and meta-data. The container is a logical entity that is made up of "parts," such as a text page or JPEG graphics file. An XPS "relationship" is a reference from one part to another part or to external resources. Similar to Microsoft's Office Open XML document format, all the elements are zipped into a single package (see Office Open XML).