The pair is virtual. vUNIT is a real token that is an index of all the other assets in our pool. vUNIT is technically backed by all the assets in the pool. However, it’s more accurate to say that it is backed by the sell function because when a user sells into vUNIT it mints the physical token. In essence, vUNIT is backed by the liquidity itself, not the assets. vUNIT is only backed when there is a positive vUNIT balance in the pool. Trustless listing pools cannot go below 0 for vUNIT balance.