Real utility of handles 3-9

[carlos]

Hello. I always want ask this:
What is the real utility in cmd of the handles 3-9 that are undefined?
The only defined handles are:

0 = STDIN
1 = STDOUT
2 = STDERR

What really useful I can do with handles 3-9 ??

[Endoro]

Look here please.

[Aacini]

And here...