 However, Schoenberg and other theorists who used his ideas as a point of departure see the theme and variations as having an underlying role in the construction of formal music, calling the process "continuing variation", and argue from this idea that the sonata-allegro form is a means of structuring the continuing variation process.Theorists of this school include Erwin Ratz and William E. Caplin.Subsections of works are sometimes analyzed as being in sonata form, in particular single movement works, such as the "Konzertstück in F minor" of Carl Maria von Weber.