Microsoft XPS

A document in the XPS document format is a paginated representation of electronic paper described in an XML-based format. The XPS document format is an open, cross-platform document format that allows customers to effortlessly create, share, print and archive paginated documents. XPS is the new document format that is the new print format for the enhanced Windows printing subsystem in Windows Vista.

XML digital Signature

Extensible Markup Language (XML) technology is now an integral part of web-based business applications. These applications require a fundamentally sound and secure infrastructure to meet the security requirements of confidentiality, endpoint authentication, message integrity, and nonrepudiation. XML signature, XML encryption, XML Key Management Specification (XKMS), Security Assertion Markup Language (SAML), and XML Access Control Markup Language (XACML) are the XML security standards that define XML vocabularies and processing rules to meet these security requirements.

An XML signature would define a series of XML elements that could be embedded in, or otherwise affiliated with, any XML document. It would allow the receiver to verify that the message has not been modified from what the sender intended.

The XML-Signature Syntax and Processing specification was a joint effort of the W3C and the IETF. It's been an official W3C Recommendation since February 2002.