A supplier who is party to a lay-by agreement (goods not delivered until fully paid, price payable in 3 or more instalments, or 2 or more if the agreement says it is lay-by, a deposit counting as an instalment) must ensure the agreement is in writing, transparent, and that the consumer receives a copy.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.