In the early 19th century, the current usage of the term "sonata" was established, both as regards form "per se", and in the sense that a fully elaborated sonata serves as a norm for concert music in general, which other forms are seen in relation to. From this point forward, the word "sonata" in music theory labels as much the abstract musical form as particular works. Hence there are references to a symphony as a "sonata for orchestra". This is referred to by William Newman as the "sonata idea".