# Language rules inheritance

`rules-` dictate how to use features available in this version of the language.

`rules-` inherit previous versions.

```
          ⋮

rules-es2017 ← es2017

     ↓

rules-es2016 ← es2016

     ↓

 rules-es6   ←  es6 (es2015)

          ⋮
```

`es2015` is provided an alias of `es6`