Cache index - how to use? (time-bend controls)

Hello,
I read about the cash Index:
“can be used to achieve more interesting time-bend effects”

This sounds nice, but is there a tutorial on how to use this?
How to set caches with index? Does it mean, I use different cache files folders?

Thanks again

You just animate the cache index. E.g. key cache index 100 at frame 0 and cache index 0 at frame 100 and you get reverse playback