Each cross-connection is rated as a high hazard (could cause death), a medium hazard (could endanger health) or a low hazard (a nuisance only, without danger to health or injury). In Australia the hazard lists and ratings for particular connections now sit in PCA Part B5; in New Zealand in NZBC acceptable solution G12/AS1.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.