The "etype" and "filetype" are used to specify the logical view of the
file and are provided in the MPI_Set_view call (pg. 240).
The user need not provide them again anytime in the program.
If the user wants to be naughty, he could free etype and
filetype while the file is still open. But for every I/O operation on
the file, I need to know what is the current etype and filetype. In
addition, there is a function MPI_Get_view (pg 242) which is supposed
to return the current etype and filetype.