Ok. As I said, there is a learning curve
I am still learning, the whole concept is only 3 weeks old.
With buying/selling MSCoins, you first decide if you want to be a
marketmaker or
ordinary buyer/seller. You are the second.
Only those who are
marketmakers can put up orders that are visible, as you can in a traditional exchange (which Enzyme/Tempest has just gone through for his/her uranium MSCoin). The difference is, Marketmakers have to display a buy
and a sell price.
If you are a
ordinary buyer/seller, you have to sell/buy into the marketmakers orders that are visible otherwise they won't get filled ("executed immediately... or not at all"). You only have to put up either buy or sell, not both (unlike the marketmakers). Your MSCoins will become available again, once the order expires or you submit another that replaces it with a very short expiry time.
Marketmakers are important as they don't rely on making money by trying to buy at the bottom and sell at the top (this is what everyone else is doing). They just make the spread between their buy and sell orders in step with whatever the price does (at least good market makers do
) . This "makes a market" as there should be some buy and sell orders no matter what the price is doing. Rather than no buyers at all time highs and no sellers at all time lows.
Most MSCoins would be certainly doomed without this (most MSCoins are likely to 'fail', if becoming the mainstream currency of the world). But it doesn't mean lessons won't be learned.
If you want to look into it further, there is the official documentation from the Core Dev available:
https://nxtforum.org/monetary-system-153/ms-official-documentation. The wiki is a good place to start.