diff --git a/ps-grammar/gprs/gprs.jsgf b/ps-grammar/gprs/gprs.jsgf
index 7d79cb3f3c3e8a87eaacfb778f2aaa18a00ebddc..ba22ccc6409740cf4db6041a87803318d6eab761 100644
--- a/ps-grammar/gprs/gprs.jsgf
+++ b/ps-grammar/gprs/gprs.jsgf
@@ -38,13 +38,13 @@ public <task> = [<robot_name>] [(would | could) you] [please] <command> [please]
 
 <second_location> = <appliance_class> | <shelf_class> | <seat_class> | <table_class> | <room_class> | <door_class> | door | seating | utensil | location | room | appliance | shelf | seat | table | somewhere | apartment | furniture;
 
-<appliance_class> = waste_bin | fridge | stove;
-<shelf_class> = bar | side_board | (right sidetable) | (left sidetable);
+<appliance_class> = (waste bin) | fridge | stove;
+<shelf_class> = bar | sideboard | (right sidetable) | (left sidetable);
 <seat_class> = <seating_class>;
 <seating_class> = sofa | armchair | bed;
-<table_class> = (kitchen table) | hallway_table | dinner_table | couch_table ;
+<table_class> = (kitchen table) | (hallway table) | (dinner table) | (couch table) ;
 <door_class> = (room door);
-<room_class> = kitchen | living_room | bedroom | hallway;
+<room_class> = kitchen | (living room) | bedroom | hallway;
 <exit_class> = (exit door) | (entry door);
 
 <preposition> = into | to | from | on;