Here is an updated version, which contains nearly the whole structure of the drs. Though the function of most of them is unknown yet. Dont get confused by all of it, if you are new to 010 editor.
Start at line 665, it says, that the first 4 Bytes in the file are a magic number. Afterwards the content starts. Bytes 5-8 are the number of models contained in the file. The next 2 x 4 Bytes are a pointers to where in the file are 2 lists. These list then point to eg the Vertices of the 3D model or the effects or sounds or the animations an object can do.
If you are lazy, you can just install pfp (https://github.com/d0c-s4vage/pfp) and convert the .drs files to .obj files with python. No ned to install 010 or understand the template below.
010 Template for the .drs files:
https://pastebin.com/X7BqaaBs
pfp example:
https://pastebin.com/9dp8reh0
(note: I used that script to get the vertices of CGeoMesh, but doing this for CDspMeshFile works similar and gives you the correct 3D model. Though to be able to print the values nicely, you have to add the .toStr() functions in fields.py in the pfp library. Also i deleted some stuff from the script, hope i didnt break anything.)