What is the correct use of the interface keyword and `@@` in JavaScript?

interface

- this JavaScript keyword is reserved for future use and @@

I see it often in the material describing the new ES6 Symbol .

For example, from jhusain / asyncgenerator :

interface Observable {
  Generator @@observer(Generator observer)
}

interface Iterable {
  Generator @@iterator()
}

      

        
        
        
      

    

Is this just figurative use? What does it mean interface

and @@

/ or correct usage if found in docs / specs / feature proposals?