An attestation is the L1 verification primitive in the Rosie architecture: a domain expert's structured, scope-bounded warrant that some specific content is correct against their area of competence.

Three properties make an attestation different from informal review:

1. Scoped. Every attestation names what the verifier is warranting and — equally important — what they are not. A customs specialist attesting to an HS-code section is not attesting to the broader interpretation's commercial reasoning; a tax attorney attesting to the withholding-rate analysis is not attesting to the customs valuation methodology. Scope discipline is what lets institutions assemble multiple attestations into a coherent certified artifact without one expert's role bleeding into another's.
2. Attached to specific content. Attestations cite the artifact at the level of granularity they cover — a section, a paragraph, occasionally an entire short document — not the document holistically as if the verifier had blessed every word. The platform's region-selection annotation pattern is designed precisely to surface this attachment in the data structure.
3. Durable. An attestation persists as part of the governance record. When the artifact is later cited, audited, or challenged, the attestation is the evidence of due diligence — the verifier's identity, scope, date, and (where the architecture supports it) the version of the underlying corpus they reviewed against.

Attestation is L1 in the verification hierarchy because it is the personal-warrant layer: one expert vouches for what they know. L2 (certification) is the institutional layer where an authority accepts accumulated L1 attestations and adds its own standing.

Worked example: a domain specialist reviews the regulatory-classification section of a compliance interpretation. Their attestation covers that section's correctness against current authoritative rulings and the cited regulatory chapter. They do not attest to the document's commercial-reasoning section or to the legal-opinion footnote — those would require different domain expertise and would carry their own attestations from the appropriate verifiers. The attestation names the specialist, the section, the date, and the regulatory baseline; the trade association's L2 certification later cites this attestation as one input to its institutional warrant.