This technical note defines a custodial criterion for distinguishing a persistent digital entity from a persistent digital profile. The criterion is witness-root custody: a construction may be classified as an entity only when its witness root is generated and held inside its closed-box boundary under a-side lineage custody. External custody, escrow, registry authority, platform root, or override capability classifies the construction as a profile. The note does not claim legal personhood, moral personhood, formal AI Act compliance, certification, or conformity assessment. Maximum claim strength: EVP-C3 — evidence model proposal.