Single-chord mode transposes one symbol and shows the full note breakdown. Sheet mode transposes every chord in a pasted chord chart.
In single-chord mode this is the chord root. In sheet mode it is the song key (used only for the key-change display).
The chord type. Major, minor, seventh chords, suspended, and extended types are all supported.
Whether enharmonic equivalents are shown with sharp (#) or flat (b) symbols. C# and Db are the same pitch - this is just a notation choice.