19. The system of claim 15 , wherein determining that the first search query includes a reference to one or more attributes associated with a first entity type comprises: determining that at least one term in the first search query appears in an attribute data store.
19. The system of claim 15 , wherein determining that the first search query includes a reference to one or more attributes associated with a first entity type comprises: determining that at least one term in the first search query appears in an attribute data store. 20. The system of claim 19 , wherein the attribute data store contains terms from previously submitted queries determined to relate to entities of the first entity type by a query classifier.