In a standard format, with a Commerce ID for privacy (what some call a "smart contract").
It works with all currencies and barter too.
1. Make an offer to purchase.
2. Describe terms.
3. Receive a counter-offer.
4. Agreement (contract)
5. Deliver on each side.
Time-stamps at each stage.
Block-chaining the list of transactions is one solution to prevent faked results.
Below describes the details of this. It solves the idea of "money".