what are the ratings in the game rating board video game rating system?
Entity Entity Entity Entity
m.0j1_t94 m.0j1_t9_ m.0j1_t9d m.0j1_tbx
GRB All GRB 15 GRB 12 GRB 18
class entity
cvg.computer_game_rating m.02vw646
cvg.computer_game_rating cvg.computer_game_rating_system
Video Game Rating Game Rating Board
none none
cvg.computer_game_rating.rating_system
Rating system
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://rdf.freebase.com/ns/> 
SELECT (?x0 AS ?value) WHERE {
SELECT DISTINCT ?x0  WHERE { 
?x0 :type.object.type :cvg.computer_game_rating . 
VALUES ?x1 { :m.02vw646 } 
?x0 :cvg.computer_game_rating.rating_system ?x1 . 
FILTER ( ?x0 != ?x1  )
}
}
(AND cvg.computer_game_rating (JOIN cvg.computer_game_rating.rating_system m.02vw646))