*** FIO\_fopen.c
On __fopen(NULL, -1, fp, mode)
the file pointer fp is closed, but _not_ deallocted. If the "reopen" fails
[that's sure because of the NULL & -1], the not-deallocated fp is left
in the memory, but NULL is returned.
==> Check out what ANSI requires.

*** HEAP\*
under heavy construction!

