Reference & Support
Glossary
Terms used across the documentation.
| Term | Meaning |
|---|---|
| Base units | An asset's smallest unit, for example satoshis for BTC. Spend caps use base units. |
| COSE key | The passkey's public key in the format the API expects, from the verified registration. |
| Display units | The amount as people write it, for example "12.5" USD₮. Quotes, payments and transfers use display units. |
| Entity key | The identifier of a wallet's owner, returned as entityKey by List wallets. |
| Passkey | A device credential (Face ID, fingerprint or device PIN) that approves payments. There is no seed phrase. |
| Paymaster | The service that pays a network fee on the wallet's behalf when fees are sponsored. |
| Safe | The smart account that holds an EVM wallet. Its owners are the customer's passkeys. |
| Spark | A Bitcoin layer for fast, fee-free transfers between Spark wallets. |
| userOp | A user operation: an EVM payment from a Safe, prepared for passkey signing. |
| USD₮0 | A second USD₮ token on Optimism. It counts as one balance with USDT. |
| XAUT | Tether Gold, a token backed by gold. |