The Organ Symphony No. 4 is a modern-classical composition. It is harmonically quite developed and consists of four movements. The 1st one is a solemn and moderately fast prelude, based on two themes. The 2nd one is a fast, tense and vigorous scherzo with a quiet and singing middle section. The 3rd one is a dreamy slow movement in which the singing main theme is alternated with two other themes, the second one a kind of lullaby. The 4th and final movement is solemn and fast and in sonata form, and characterised by a main theme with a running bass. Registration indications (based upon the Hauptwerk sound set of the Mutin / Cavaillé-Coll organ of the Notre Dame in Metz) are intended as a help and are mainly notated as in late French romantic organ music (Widor, Vierne). In 2016 I have revised the piece, checking every registration indication and every bar and I can assure now that the piece is entirely playable and that it will sound great if you follow my registration indications. The recording (digital performance in Sibelius 5 with Garritan Personal Orchestra, not Hauptwerk, of the former version of 2013) gives, besides the registration indications, a scant indication of the sound I want.