Extensible Forms Description Language (XFDL) is a use of the Extensible Markup Language (XML) that provides a standard way to define the data fields and layout for a complex business or government form for digital storage and display. An XFDL form can be sent to a Web user as an XML page. XFDL makes it possible to sign an XFDL page with one or more digital certificates. XFDL also describes a syntax for inline mathematical and conditional expressions. XFDL combines the Universal Forms Definition Language (UFDL), developed earlier, with XML.
PureEdge, an e-commerce standards firm, formerly called UWI.com, and World Wide Web Consortium (W3C) editor Tim Bray introduced XFDL in 1998 as the world's first open standard for secure, legally-binding XML documents. Since then, vendors such as GTE, CommerceOne, and Verisign have moved to support or endorse XDFL in their products.