Basicly, here is the full story:
First, westwood released the mod tools. This first release included the w3d_file.h straight from the code of renegade (there were a few bits missing that were in other files but a few answers from Greg Hjelstrom and we had the whole thing)
Then, westwood released a new mod tools, only difference was that the w3d_file.h was gone. Aparently, releasing it generally broke some licence with Discreet. Greg Hjelstrom said:
1.it was NOT ok to make a w3d->some format like 3ds converter (licence violation)
but 2.it was ok to make a w3d import script for gmax (he specificly checked with discreet on this)
Then, Abjab started working on his w3d->gmax converter. He wrote quite a bit of it. Around this time is when the untextured copies of e.g. l10 and others started showing up.
Next, there was a beta test (closed, script modified not to save anything and other stuff)
Then, sometime after that Abjab disappeared from the face of the earth (He hasnt been heard from since)
Next, Dante (who had the unencrypted script) gave it to me to work on.
Also, Seagle released an unrelated script that had only limited features.
Then, I released the encrypted script that we have now (with the encryption only being there because Abjab insisted on it way back when and hes not around anymore to say otherwise

)
So, the w3d file format is documented (if you want to get all the info I have, go to
http://www.sourceforge.net/projects/rentools and download the w3dump program, thats got the info you need in it (including the w3d_file.h & stuff)