Yeah, LZB internally is based on fixed blocks - but on a system with block lengths down to 50 meters (as in the Stammstrecke München [1]), the difference is negligible.

Crazy to see that SelTrac was actually developed in Berlin, failed there, but is still in widespread use across the world.

[1] https://de.wikipedia.org/wiki/Stammstrecke_(S-Bahn_M%C3%BCnc...