[css3-writing-modes] Intended scenarios of use of text-orientation:upright?

What are the intended scenarios of use of text-orientation:upright (or 
stacked, if it is renamed to that)? I realize that once it's in, users 
will do whatever they want with it, but surely there is a motivation.

In particular, is it intended for scenarios in the CJK world or for 
scenarios in the Western world?

Thanks,
Eric.