Tags are a separate mechanism, since different implementations need different specs to be tagged.

You can tag specs using the following command:

```
./bin/mspec tag path/to/spec/file.rb
```

This should add a spec or create a new file with the spec in spec/tags. The spec should be there for both 1.9 and 2.0 mode, so both in spec/tags/19 and spec/tags/20.