A named validation profile that can be applied to a document. Profile URIs follow CIUS (Core Invoice Usage Specification) conventions. Examples: "urn:cen.eu:en16931:2017" — EN 16931:2017 (base) "urn:cen.eu:en16931:2026" — EN 16931-1:2026 (ViDA-ready) "urn:fdc:peppol.eu:2017:poacc:billing:3.0" — Peppol BIS 3.0 "zatca:fatoorah:2.0" — ZATCA Phase 2 (FATOORA) "eta:einvoice:1.0" — Egypt ETA