Dates and listening details already known to Music Journals.
Composed 1783
Ludwig von Köchel initially assigned the work to 1778 in Paris; however, subsequent watermark and paper studies by Alan Tyson and Wolfgang Plath established that it was composed in 1783, likely in Vienna or Salzburg.
Composed 1932–1959
The pieces were not conceived as a single cycle, but composed and catalogued in four separate groups: FP 63 (Nos. 1–10, 1932–1934), FP 113 (Nos. 11–12, 1941), FP 170 (Nos. 13–14, 1958), and FP 176 (No. 15, 1959). Also catalogued as 15 Improvisations / Les 15 Improvisations pour piano.
Composed 1784
No exact source-backed composition date resolved in the automated pass; reviewed 2026-08-22.
Composed 1903–1904
Composed 1903–1904 (frequently cited simply as 1904). Also styled L'Isle joyeuse. Catalogue designations are CD 109 (2001 catalogue) and L. 106 (1977 catalogue).