Propagated clock
Beginner
The clock as it really behaves after the tree is built, with real travel delays.
Novice
A clock whose arrival time at each flip-flop is calculated from the real delays of the buffers and wires in the built network, instead of being assumed.
Expert
Switched on with set_propagated_clock. Each sink then has its own latency and edge rate, variation derates apply to clock cells, and common-path credit (CPPR) becomes meaningful. All timing work after CTS, including signoff, uses propagated clocks.