What does the "Span" AI option actually do?

I've seen this option in the AI mode selector recently and I've got no idea what it actually does, other than act like the "random" setting. Anyone have any idea how it's different?
Edit: Also, what does the "risk" parameter do? I suppose it seems self explanatory, but I don't notice much of a change when I lower it or increase it...

 

From the 0.9 devblog :

The risk parameter modify how brave the AI is : the higher it is, the faster it will drive, the lower the slower (it's especially noticeable in the tight corners)

 

Thanks!