Sub-accounts

Sub-accounts allow users access to multiple (up to 256) virtual accounts that are entirely isolated from one another. Although multiple separate Ethereum addresses could be used, sub-accounts are often more efficient and convenient because their operations can be grouped together in a batch without setting approvals.

Since an account can only have one controller at a time (except for mid-transaction), sub-accounts are also the only way an Ethereum account can hold multiple vault borrows concurrently.

The EVC also maintains a look-up mapping so sub-accounts can be easily resolved to owner addresses, on- or off-chain. This mapping is populated when an address interacts with the EVC for the first time. In order to resolve a sub-account, the getAccountOwner function should be called with a sub-account address. It will either return the account's primary address, or revert with an error if the account has not yet interacted with the EVC.