The short-unit attribute works as such:
It represents the values as units.
For values: 0 to Num, Num will be divided by Num with "A" following the number.
For values: num to 1000*Num, value will be divided by 1000*Num with "B" following the number.
For values: 1000*num and up, value will be divided by 1000*1000*num with "C" following the number.
You can mingle with the base used (so instead of 1000 you can use 1024 which is used in computer related metrics)
Another nuance is that if you use a # in front of an unit, that unit will ALWAYS be used when formatting scale labels or value boxes or other appropriate elements. Something like
will always use PiB as unit, even if values are smaller, so they will get converted to things like 0.0001PiB