I have that
SHIII Mission Editor Manual v17 here, and have been waiting of someone of the group to reply to email attempts, but nothing yet, so I'll go ahead an put it to a site with better bandwidth than what I have, and change the link later...
The cover of it has:
Silent Hunter III
Mission Editor
Users Guide
Written and maintained by Dietrich on behalf of
17. Unterseebootsflottile »Nordfront«
http://nordfront.org/xvii/
Version v17
19 Mar 2010
It is probably the most comprehensive version there is, unless something is out there in the wild, but not just inside someone's grey matter...
It is a zip file, has a named folder, with the pdf inside of that.
