Only used by "Select Tone". A whole number from 1 upwards — 1 is the
first tone in the vehicle's list, and most cars carry three or four (wail,
yelp, phaser and so on). The key shows the name of the tone it will select,
so you can see at once whether you picked the one you meant; a number the
vehicle has no tone for shows as "T" and the number instead of a name. If you
want to walk whatever list the current car has, use a Tone Dial instead.