On classical French organs, the plein jeu is a principal-based plenum registration.
It includes the Montres, Bourdons, Prestants and Doublettes (Principals 16′, 8′, 4′ and 2′) and the Fournitures and Cymbales (lower- and higher-pitched mixtures).
[1] The classical French organ also allows for a reed-based registration; the grand jeu, which used a loud combination of reed stops (usually consist of trompette 8′, Clarion 4′, Prestant 4′ and Cornet séparé (or Cornet V), which comprises Bourdon 8′, 4′, 2′, Nasard 22⁄3′, Tierce 13⁄5′.
The 'Plein Jeu' is a mixture stop voiced fairly boldly where a powerful effect is needed, particularly when added to the Great Diapason Chorus.
As the stop progresses upward on the keyboard, the notes "break" back to the next lower octave or fifth.