For propagation material produced in house (a nursery being any place where propagation material is raised, in-house selection of grafting material included), a quality control system monitors for visible signs of pests and diseases at regular set intervals, and current records identify the source mother plant or the originating field crop. If the material is for the farm's own use only, in-house records of monitoring and propagation are enough, and where rootstocks are used their origin is documented.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.