PoR and Mint Budget

XAUm can be minted and redeemed on multiple blockchains, while ensuring that the sum of totalSupply on all chains does not exceed the reserve amount given by the PoR Oracle. The PoR Oracle that XAUm relies on is deployed on the Ethereum mainnet, and references the total physical fine weight of all gold bars under custody.

After subtracting the sum of totalSupply of XAUm on all chains from the reserve amount endorsed by the Oracle, the resulting difference is called the Global Mint Budget, which is the total amount of new XAUm that can be further minted on chains. This occurs when a new physical bars is added to the inventory, prior to the minting of XAUm. Each time the reserve is increased, or XAUm is redeemed, the value of the Global Mint Budget is increased.

The mint budget allocated to each chain is called the Local Mint Budget. Whenever the reserve increases, the local mint budget on Ethereum increases. Each time XAUm on a particular chain is redeemed, its local mint budget also increases. Matrixdock uses cross-chain protocols to schedule transfer of local mint budgets between chains. When minting XAUm, the amount minted cannot exceed the local mint budget on the current chain.