These return codes are possible:
- 0
- Normal completion.
- 4
- Member already exists in the output library and NOREPL was
specified. The original member is unchanged.
- 8
- File not open. FTOPEN was not used before FTCLOSE.
- 12
- Output file in use. ENQ failed.
- 16
- Skeleton library or output file not allocated.
- 20
- Severe error.