file% = FNopentempfile
      IF file% = 0 ERROR 100, "Failed to open temp file"
      PRINT #file%, "Hello world!"
      PTR#file% = 0
      INPUT #file%, message$
      CLOSE #file%
      PRINT message$
      END

      DEF FNopentempfile
      LOCAL pname%, hfile%, chan%
      OPEN_EXISTING = 3
      FILE_FLAG_DELETE_ON_CLOSE = &4000000
      GENERIC_READ = &80000000
      GENERIC_WRITE = &40000000
      INVALID_HANDLE_VALUE = -1
      DIM pname% LOCAL 260
      FOR chan% = 5 TO 12
        IF @hfile%(chan%) = 0 EXIT FOR
      NEXT
      IF chan% > 12 THEN = 0
      SYS "GetTempFileName", @tmp$, "BBC", 0, pname%
      SYS "CreateFile", $$pname%, GENERIC_READ OR GENERIC_WRITE, 0, 0, \
      \                 OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, 0 TO hfile%
      IF hfile% = INVALID_HANDLE_VALUE THEN = 0
      @hfile%(chan%) = hfile%
      = chan%