its keeping a collection of 'chairs' in a list called 'room'
Hence Chairs[] should be a field of Room, and not that a chair should be called Room Its called 'room' becuase thats the example given in the official docs
Then it is one of the things that was possible adding to your confusion about types. It a really really stupid way to name an instance of "Chair", because as you have just shown it confusing the issue between "Is A", and "Contains A".ARoom may Conatian A Chair, and as such any Type TRoom can have fields of lists of Chairs or Arrays of chairs, or pointers to Banks of chair, in short in may conatin Chairs.
A Chair on the other hand Is Not A room, it is in no way similar to a room (Cept they both might have fleas in them), and shouldnt be called A room at all