Every edge declares its own evidence.

The four-state taxonomy distinguishes the absence of evidence from the absence of state-knowledge. The first three states apply at the edge level. Observed evidence comes from a named public source. Derived evidence follows by transparent inference from observable structural data. Inferred evidence rests on patterns and carries explicit confidence tagging. The fourth state, Unknown, applies at the agent level for regulatory dimensions where evidence has not been ascertained either way. The discipline matters because the difference between "the institution does not have X" and "we have not established whether the institution has X" carries regulatory consequence. The substrate enforces that distinction in the schema.