Those are bitUSD/bitEUR/bitCNY/bitBTC/bitGOLD/..., they are called Smart Coin in bitshares terminology. The collateral is decentralized. Every Bitshares user can lock some BTS as collateral to issue smart coins. No central point of failure.
More info here: https://bitshares.org/technology/price-stable-cryptocurrencies/

Currently Fiat deposit is closed, but you can deposit many other tokens, they will be guaranteed by openledger (so centralized). Then you can sell it for a smart coin to avoid the risk of default of openledger. You will then be able to go out through another gateway (rudex, cryptobridge, ...)