The LIN is a new signal management protocol that has recently been observed on Volkswagen group cars, including (but not only) Audi A4 crossover, Audi A4 Avant, Audi Q8 and Skoda Octavia Wagon. The LIN adapter has 6 terminals that transform data into 3 analog signals: rear lights, fog lights and position lights. On vehicles equipped with this protocol these 3 signals travel on a single cable. Using a voltmeter you can find the presence of this protocol by virtue of the 7V reading in DC, regardless of whether the lights are on or not. Brakes and arrows use a normal 12V signal instead. The trailer's position lights may be connected to the vehicle number plate lamps, which is similarly a standard 12V signal (L and R joined together).
WARNING: depending on the vehicle layout, the signal scheme may vary.

List of cars that could equip the LIN protocol (in update):

Škoda Octavia and Octavia Kombi from 2020, Škoda Enyaq, Škoda Karoq from 2022, Škoda Superb from 2020, VW ID4, VW Golf Mk8, Audi E-tron, Audi, A3 S-LINE end of 2022, Audi A6 and A6 Avant from 2020, Audi A7 from 2018
(attention to cars equipped with Skoda - TOP LED, VW - IQ Lights, Audi - Matrix LED)