This document provides a definition of a standard Data Format Description Language (DFDL). This language allows description of text, dense binary, and legacy data formats in a vendor- neutral declarative manner. DFDL is an extension to the XML Schema Description Language (XSDL).
 
DFDL is a language for describing data formats. A DFDL description allows data to be read from its native format and to be presented as an instance of an information set or indeed converted to the corresponding XML document. DFDL also allows data to be taken from an instance of an information set and written out to its native format.
 
DFDL achieves this by leveraging W3C XML Schema Definition Language (XSDL) 1.0.
 
An XML schema is written for the logical model of the data. The schema is augmented with special DFDL annotations. These annotations are used to describe the native representation of the data. This is an established approach that is already being used today in commercial systems.