Suzuki 2 Strokes

Last summer my T500 broke down when I believe it over charged and destroyed the battery. I use a Mighty Max YTX4L-BS battery. I use this in 6 of my bikes which is handy for replacing or swapping batteries. The other bikes are all British and all have a Tympanium regulator/rectifier. So I am going to replace the Suzuki regulator and plate rectifier with a Tympanium. I found this diagram on this forum:

viewtopic.php?f=2&t=4858&p=109480&hilit ... um#p109480

Can anyone tell me what is the purpose of the Red/Green wire which goes from the alternator to the left control grip switch terminal marked "SE"? This wire bypasses the regulator rectifier.

The alternator has charging coils & lighting coils.
The charging coils are connected directly to the rectifier. The handlebar switch that turns the lights on also connects the lighting coils to the rectifier.
This matches the alternator output the the load.