Keys derived from a single base derivation key use unique derivation data under ISO 11568 so that each device gets its own initial key, and the base key is never itself loaded into a POI; using one BDK with an identical KSN in several injection systems, or repeatedly in a single system, breaches uniqueness.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.