The letters C, D, E, F, G, A and B are used to indicate notes.
Notes can be [sharpened][sharp] by appending a hash symbol (#) or [flattened][flat] by appending an exclaimation mark (!).
For example "C#" is used to indicate a C♯, and "D!" is used to indicate a D♭.
Octaves: By default, the notes are in the 4th octave. A numeric value can be appended after the note to indicate a different octave.
For example, "A5" indicates an A in the 5th octave, and "G#3" indicates a G♯ in the third octave.