This is how Stag controls its own liquidity and other reserve assets, such as ELK, by selling STAG at a discount in exchange for these assets. The protocol gives the bonder terms of exchange such as the bond price, the amount of STAG tokens entitled to the bonder, and the vesting term for said bonds. The bonder can claim some of the rewards (STAG tokens) as they vest, and at the end of the vesting term, the full amount will be claimable.