Because Build L3 artifacts can only be trusted if the platform's provenance is unforgeable and its builds isolated, consumers should assess a platform against the adversaries it must resist (project contributors, project maintainers and platform administrators, each with the abilities the specification lists) and against at least five components of the build model: external parameters (how they are processed and kept complete in provenance), control plane (administration and privileged access, provenance generation, development practices, creation of build environments, management of cryptographic secrets), build environments (isolation technology, creation and destruction, network access), caches (types, population, validation) and output storage (preventing builds reading or overwriting each other's outputs). Platforms may attest for themselves and publish the evidence, or have an independent auditor certify them.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.