how much the files can be opened simultaneously?

I read the UTL_FILE package and found a comment in the package
"As of 8.0.6, you can have a maximum of 50 files open simultaneously."
I want to know the mean of the comment. It means the maxinum 50 is in one procedure or in the global? I want use a procedure write a file. But the procedure may be called by many many users(for example 10000) simultaneously. I want to know the result in this case.
My english is very poor. Hope you unterstand me.
please help
thanks very much.