The QWD format is even harder to understand than the DEM format. Please look in the ``Unofficial QWD format description''. The current version is http://www.planetquake.com/demospecs/qwd.
You will understand my textual representation of the QWD format by inspecting a sample file and reading a bit about the structure in the mentioned document.
If someone is willing to write a documentation of my QWD text format please inform me and your document will be included right here.