@gregory_nico Ossification is not fossilization. It implies an area of the code that is more robust and distinct from higher areas of change. The difference is between the skeletal structure versus blood veins.

In Bitcoin this would mean hard limits to blocksize and supply, core opcodes among other things. Innovations and many opcodes can be pushed to L2. Major security updates such as Quantum Resistance or obvious fundamental bug introduction from new technologies, can still be part of an ossified base.