I have seen Exchanges mentioned as a use of BitShares repeatedly. However, I have not seen anyone describe how they will actually work.
I understand the BitBTC, BitUSD, etc. concepts. None of these require the system to actually hold BTC, USD, or whatever the underlying asset may be.
Is this the idea for Exchanges? E.g. once you have created BitBTC and BitUSD, you can trade your BitBTC and BitUSD without ever owning or actually trading the underlying assets? Or you could hold BitLTC, BitDOGE, etc. and trade all of them versus each other and BitBTC, BitUSD, etc.?