The following is just my guessing and shouldn't be taken
any sort of firm knowledge on my part:

The film is German. It is probably from the 1920s. Kodak changed
116 film from six exposures to eight in 1932 and I'm pretty sure
the others followed soon after that. If I'm interpreting D-12
correctly it is a double length version of D-6 which was the
German Agfa name for 116 film. If so, the film will be about
4 1/4 feet long and may not fit all 116 reels for developing
tanks. There shouldn't be any trouble with short roll 70mm reels
though.  

The film is probably ortho, which would allow you to develop
by inspection under a Kodak #2 safelight. But if you don't know
for sure it isn't a good risk. I have no information on how long
the development should be, but it would almost certainly be
somewhat longer than any modern film.  

It is possible that the film will identify itself on the front
end of the backing paper. If you have a #2 safelight (I have
sometimes used a mini flashlight with a #25 gel filter aimed
at the wall as a substitute which seems to work safely) then
if the film does not identify itself as panchromatic, you can
feel pretty confident about inspecting the film during development.

Peter.