Frontend is the name of the main menu music for the Re-Volt games. Each version has the same song, but they have some differences including extra parts of the song and changes in fidelity.
Like the other versions, this song plays at the main menu. It was probably originally intended as title screen music, but Re-Volt does not contain a title screen and instead just sends the player to the main menu. Because there is no USF rip, the music was recorded using a real Nintendo 64 console.