For this example, we introduce the notion of the scene itself being a “referenceable object”.
Previously we would allowed objects in the scene to be referenceable, such as Object[<|”Color” -> “Blue”|>] referring to “the blue object”, and so ObjectValue[<|”Color” -> “Blue”|>], “Y”] was a way to refer to “the Y position of the blue object”. But now Object[“InputScene”] is a referenceable object, and a scene property ObjectCount has been added, so ObjectValue[“InputScene”, “ObjectCount”] can be used, for example, when producing generalized rules.