Say a user deposits 1000 USDD to Bitlend when the exchange rate is .02. That user would receive 50,000 bUSDD (1000 / .02).
After several months, the user decides it is time to withdraw their USDD from the protocol. At that time, the exchange rate is .02158.
The user’s 50000 bUSDD is now equal to 1079 USDD (50000 * .02158).
The user has the option to redeem all 50000 bUSDD to withdraw all 1079 USDD, or they could remove any portion they choose.