Thanks. That was the answer I was hoping for with the blockchain making all market actions public and transparent.

All bids, asks etc are recorded on the blockchain, so require the user to pay the usual transaction fee. By default this is 0.5, but you can reduce it down to 0.1 in the preferences.

Canceling an issued order costs another 0.1, because the cancel goes into the blockchain too.

The market engine matches orders when 2 opposing sides have overlapping prices. At that point the transaction cant be canceled, at least not partially.

Or just the transactions generated from the market engine?

And if so, then what are the fees?