Assets supported by Bitlend are incorporated using a bToken contract. When a user supplies assets to the protocol, they mint bTokens, which are representative of the assets they have supplied. bTokens may be held to earn interest, or used as collateral for borrowing.
There are currently two types of bTokens: BBrc20 and BBtt. Though both types expose the EIP-20 interface, BBrc20 wraps an underlying BRC-20 asset, while BBtt simply wraps BTT itself. As such, the core functions which involve transferring an asset into the protocol have slightly different interfaces depending on the type, each of which is shown below.