At every scale CEG operates on, key, occurrence, agent, fleet, cell, federation, biosphere, “self” means the already-relationally-constituted entity speaking at that scale. The cross-attestations that constituted the entity are upstream of the moment it speaks; when it then emits a self-attestation (the envelope’s witness_relation: self, declares its own confidence, reports its own occurrence_id, names its own hardware_class, signs accord:lifecycle:active), that is the relational composition speaking AS itself, not a Cartesian atom asserting pre-relational identity.
The substrate cannot require cross-attestation as a precondition for self-attestation because the cross-attestations are what constitute the self in the first place. They are upstream, not downstream gates. The fractal nesting is the point.
The common misread to avoid: a reader importing Cartesian-individualist defaults from PGP / X.509 / DID atomic-principal frames will see witness_relation: self and think “a lone principal is asserting its own state; surely the substrate should require cross-attestation before admitting.” That reading is wrong. If you find yourself thinking the spec should add a cross-attestation gate before admitting this self-attestation, pause, cross-attestation already happened upstream; the self-attestation is its downstream voice.