6c6,14
<     -#      # Compression level, with # being any value from 1 to 12
---
>     -1  # Compression level 1
>     -2  # Compression level 2
>     -3  # Compression level 3
>     -4  # Compression level 4
>     -5  # Compression level 5
>     -6  # Compression level 6
>     -7  # Compression level 7
>     -8  # Compression level 8
>     -9  # Compression level 9