The Extensible Data Format (XDF) is an XML

Extensible Markup Language

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

 standard (specified as a DTD

Document Type Definition

Document Type Definition is a set of markup declarations that define a document type for SGML-family markup languages...

) developed by NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

, meant to be used throughout scientific disciplines. In many ways it is akin to XSIL

XSIL

XSIL is an XML-based transport language for scientific data, supporting the inclusion of both in-file data and metadata. The language comes with an extensible Java object model...

, Extensible Scientific Interchange Language. NASA provides two XDF API

Application programming interface

An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...

s, in Perl

Perl

Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...

 and in Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

.

XDF is used to store high dimensional data and information related to it in compact XML format. The purpose is to have interchangeable and high quality format that can be used as a main archive format for this kind of data.

The XDF project and related development have been halted (2002,2006). The existing information have been archived to the UMD Astronomy Information and Knowledge Group site as a reference.