The paint markings put on fasteners and other parts of Mercedes cars on the production line has been discussed several times on our Forum. Just put in search key "dotology" and you will find many postings.
In principle, these dots are part of quality control. A paint dab indicates "assembly complete", "torque applied", others "fluid filled", "front suspension aligned", "steering and toe-in aligned" and so on.
These markings were put on by workers in the factory, with a brush. Colours red, yellow, pale green, and blue.
See https://www.sl113.org/forums/index.php?topic=26299.msg188316#msg188316
PS. I added this in Tech Manual under "Chassis and Body"
Hans,
Yes, thank you. I am somewhat familiar with the topic, been studying it for a while. I am enclosing my "collection" gathered from many posts. But I have obvious gaps, so thanks - it is also about a number of other topics, activities, tasks completed etc., as you said.
In this particular question I was after what could various colours mean in this paticular instance. I knew that dots were about confirming tightening of screws or nuts in important places, torques perhaps, oil filling, etc. What I did not understand was this instance of light green (which I could not recognize on the picture, thought it was white) and yellow on top of it as well as some other "multi-colour" places.