Custody means who holds the keys: you (self-custody) or a third party (exchange or custodian).
CEX accounts are custodial. Self-custody removes counterparty risk but adds operational responsibility.
In research workflows, Custody is usually interpreted with Centralized exchange, Crypto wallet, KYC, and Multisig rather than as a standalone signal. Operational security mistakes are irreversible on most public chains. Verify networks and destinations before large transfers.