FUNCTION c_hdropen (fd, file, access)
int *fd; char *file; long *access;
File descriptor for the opened AVHRR archive header file.
Host file name for the associated AVHRR archive header file to be opened.
The type of access requested (IREAD, IWRITE, IUPDATE).
The specified file is opened with the appropriate access privileges.
c_hdropen() returns
E_SUCC (0) --> Successful completion. E_FAIL (-1) --> Operation failed.