Need help for 3rd brake

Hello everyone. I'm trying in DIY to learn how to script / repaire some parts of cars i ve downloaded.

On my tests, i'm trying to understand on a car ( Mercedes e200 ) how to stop the lowhighbeam (at night) working on the 3rd brake light. I 've found in e200.beam the glowmap where i can find the script for the lights in night, but i dont understand how to create a difference between Left / Right and the 3rd taillight.. (Sorry for my English).

The Glowmap :
"glowMap":{
"signal1":{"simpleFunction":{"signal_L":0.49}, "off":"signal1", "on":"orange", "on_intense":"orange"},
"signal2":{"simpleFunction":{"signal_R":0.49}, "off":"signal2", "on":"orange", "on_intense":"orange"},
"svetzad":{"simpleFunction":{"lowhighbeam":0.49,"brake":0.49}, "off":"svetzad", "on":"red", "on_intense":"red"},
"svetzad":{"simpleFunction":{"lowhighbeam":0.49,"brake":0.49}, "off":"svetzad", "on":"red", "on_intense":"red"},
"svetzad":{"simpleFunction":{"lowhighbeam":0.49,"brake":0.49}, "off":"svetzad", "on":"red", "on_intense":"red"},
"svet":{"simpleFunction":{"lowbeam":0.49,"highbeam":1}, "off":"svet", "on":"svet", "on_intense":"white"},
"gauges":{"simpleFunction":{"lowbeam":0.49,"highbeam":1}, "off":"gauges", "on":"gausvet", "on_intense":"gausvet"},
"lightper2":{"simpleFunction":{"lowbeam":0.49,"highbeam":1}, "off":"svet", "on":"white", "on_intense":"white"},
"parking1":{"simpleFunction":{"reverse":1}, "off":"parking1", "on":"white", "on_intense":"white"},


When i m looking on other cars scripts, i can see more lines for lowhighbeam. But i dont understand what is missing on the e200 script.

Thanks for your help. (I dont want to leak a modified car, i just want to learn how works the beamng files.)