%N scropen %F $MIR/src/subs/scrio.c
%D Open a scratch file.
%: scratch-i/o
%B
FORTRAN call sequence:
        subroutine scropen(tno)
        integer tno

  This opens a scratch file, and readies it for use.
  Scratch files will be removed when they are closed, multiple scratch
  files are allowed, and they always live in the current directory, unless
  the $TMPDIR environment variable points to another directory.

  Output:
    tno         The handle of the scratch file.                         
