Nearly all sources describe Grand Cornet as a Cornet which supports the 16' harmonic series in the manuals, or the 32' harmonic series in the pedal. However, in the classical French organ, Grand Cornet was the name sometimes given to the Cornet on the Grand Orgue, and many examples in actual usage support the unison rather than the sub-octave (see below). The classical French Grand Cornet, according to Dom Bedos, had a compass of 2 octaves, from middle C upwards. Bedos writes: ... the Grand Cornet has the function of strengthening and brightening the treble of the Grand Jeu, which contains the Trompettes and Clairons. ... The Grand Cornet must increase in strength as the Trompettes and Clairons weaken, and conversely. The name Gross Cornet appears only in a list of mixture stops in Irwin's appendix on Mixtures. The only information he gives is �16' �; we assume it to be a synonym for Grand Cornet.
Of the fifty examples of Grand Cornet in Osiris, fifteen are known to support the unison, and seven are known to support the sub-octave. They range from III to XI ranks.