Basically a blockchain that stores what was conveyed, with an ID number that may or may not be traceable.
Companies add value to that free data: wealth translation and promise assurance.
Basic structure:
Initiating promise: 1 BTC
Notice - accept: 20 LTC
Promise: 20 LTC
Deliver: 20 LTC
Deliver: 1 BTC
End transaction.
Does that make sense?
Research atomic cross-chain transactions. Take a look at what bitsquare.io is doing for example, might help flesh out your idea.
Bitsquare is on the right idea with its message-based system, but is convoluting some ideas. Collateral and fees being two. The idea expressed above breaks the concepts into constituent parts and each becomes interchangeable.
