Thanks a lot for the upload.
> Looking at the README.Debian file, if ngspice is "just" under non-free
> because of the non-free document, moving the documentation into a
> dedicated package could
> be a solution (instead of merging it).
You are right, I will make ngspice-doc a special package. I have gone through the licenses of the files in the program, there is a variety of them. I removed a few files with unsuitable licenses but there are still at least two files I have to remove because they are not DFSG. Making the new copyright file took a long time.
I don't have time to work on it now but I will try to make it DFSG in the autumn or at least before next ngspice release.