There is no official "standard" for audio systems. As long as you stay consistent throughout the system, it will work properly. It is a little known fact that most electrons are color-blind :-)
Note...
CAR AUDIO FRONT SPAEKERS LOCATION: DOORS
LEFT FRONT SPEAKER POSITIVE (+) WIRE: TAN
LEFT FRONT SPEAKER NEGATIVE(-) WIRE: GRAY
RIGHT FRONT SPEAKER POSITIVE (+) WIRE: LIGHT GREEN
RIGHT FRONT SPEAKER...