There is information here for DFDL Users, as well as for Daffodil Developers.
What is Daffodil?
A program that reads a DFDL Schema, and parses data as described by that schema to create an XML document.
In the future there will be a symmetric data serializer (or unparser as we like to call it.)DFDL is capable of describing many data formats, including textual and binary, commercial record-oriented, scientific and numeric, modern and legacy, and many industry standards. It leverages XML technology and concepts, using a subset of W3C XML schema type system and annotations to describe such data. Daffodil uses this description to parse data into an XML infoset for ingestion and validation.