The DM2 format is a nice and compact file format. Please look in the ``Unofficial DM2 format description''. The current version is http://www.planetquake.com/demospecs/dm2.
You will understand my textual representation of the DM2 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 DM2 text format please inform me and your document will be included right here.