Collateral Wrappers

Collateral wrappers allow a Pool to recognize collateral that exists in a wrapped form for a loan. This facility is useful for implementing a number of extensions to the Pool, such as bundles and airdrop receivers.

Collateral wrappers are implemented as an ERC721 token that the Pool takes custody of instead of the native collateral token for a loan. Collateral wrappers implement the ICollateralWrapper interface, which allows a Pool to enumerate the underlying collateral for validation with its collateral filter, and allows a collateral liquidator to unwrap the underlying collateral for liquidation.

The two official collateral wrappers are the BundleCollateralWrapper, which can be used to create reusable collateral bundles, and the ERC1155CollateralWrapper, which gives Pools indirect support for ERC1155 collateral with loans.

Pools may recognize up to five collateral wrapper contracts, which are bound to the Pool implementation contract at deployment time.