Notch on the rim

[Tam92]

Hi friends, I have noticed the presence of some notches along the wheel rim and I don't unerstand the reason of this notches.
I have underlined this feature in the photo.
Does someone knows something about?

Safety stuff, solid german engineering around 1930 by Kronprinz, Solingen.

Stops the tire rim to slip in the deep bed in case of pressure failure, dismantling from the wheel consequently.

Tires are a bit tricky to assemble, working contrary compared to standard wheels.

Cheers, Frank