manual focus – What are these numbers below the distance scale of my lens?

On my Canon EF35mm F2 IS USM (my first prime lens ever which I just bought used) there are the numbers 22, 11, (line with red dot), 11, 22 written below the distance scale.

From the manual of the lense I learned that they are seemingly called “distance index”, but the manual doesn’t mention what they are. Even googling this word, and also several other related search terms like “lens numbers below distance scale”, doesn’t find me anything.

What do the numbers and the red dot mean, and what are they used for?

enter image description here