POC migration is the movement of a session center of activity from one profile period to another. A higher POC can describe value being established at higher prices; a lower migration describes the opposite.
The phrase is descriptive, not directional proof. A POC can migrate while the broader range remains balanced, and a late move can change the profile visible earlier.
Compare migration with range expansion, value-area movement, and the handoff between Asia, London, and the US.