What are the abbreviations or letters on Police dash cam footage?

[tdavis0724]

Hello, does anyone know what the various letters often shown on Police car dash cam footage mean? I know they probably vary across departments and different states/countries, but does anyone know any of the other ones I've listed below?
L seems to mean Lights are on
S is siren is on
B is on when the car's brakes are applied

What about A, C, or G? And does anyone know of any other ones that are pretty standard?

I saw a C displayed on one video as the officer was making a sharp turn and then the C went away.
Also, in another video I saw a G appear right after the officer said something about reaching a speed of 100mph. A few seconds later, the officer had to hit his brakes and slow down and the G went away.

Thanks for the help!