how to understand the long numbers in the manual?

[abrogard]

I use VLC for changing mkv to 25 fps mp4 it does a mighty job. I'm told it uses ffmpeg.

I thought i might somehow find the commands it uses to do this because myself and the ffmpeg helpers I found couldn't come up with a way to do it.

So I got the command list by using VLC -H.

Excellent. But what are these long numbers, how am I to understand them?
For instance:

Screen Input (screen)
--screen-fps=<float [-340282346638528859811704183484516925440.000000 .. 340282346638528859811704183484516925440.000000]>

And I have mentioned what I am trying to achieve so's if anyone knows the answer we can perhaps cut to the chase ...