The frequencies in Hz are:
- #define FI_A 440
- #define FI_As 466
- #define FI_B 494
- #define FI_C 523
- #define FI_Cs 554
- #define FI_D 587
- #define FI_Ds 622
- #define FI_E 659
- #define FI_F 698
- #define FI_Fs 740
- #define FI_G 784
- #define FI_Gs 831
The three digit number is the frequency. For example, FI Gs 831 is 831 Hz.