Officials must keep, for each procurement, documentation commensurate with its scale, scope and risk (covering the requirement, the process, how value for money was achieved, approvals and decisions with reasons), must have access to evidence of the agreement (contract, purchase order, invoice or receipt), and must retain records under the Archives Act 1983.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.