There are a lot of non-ubuntu questions that are off-topic but *not* unix questions. That should also be an option in the off-topic flag dialogue.

> Questions on **Linux or Unix** which don't involve Ubuntu are off-topic here, but can be asked on [Unix & Linux Stack Exchange][1]. For questions on **Windows** and **Mac OS** or any other operating system, please contact their respective official support centers or try [Super User][2] or [Ask Different][3].


  [1]: https://unix.stackexchange.com/about
  [2]: https://superuser.com/
  [3]: https://apple.stackexchange.com/