The coordinator is the person or organization that carries out coordination (3.6), meaning the work of finding and involving the parties concerned, mediating between them, keeping them informed and planning so that disclosure can happen (3.3); CERTs, CSIRTs and industry bodies commonly play the role. ISO/IEC 30111 6.5.3.5 points vendors to this clause and to clause 8 when reports are shared with coordinators, and the CRA harmonized-standard draft cites it together with 8.1 for bringing a coordinator in.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.