As a simple Engineer, all this law stuff is news to me, and very interesting! I had not thought of the exchange of goods and services in such detail. Could you point me in the direction of a source for this material, or is the above a distillation of many? I am suddenly curious about the details...
It has given me a greater appreciation of delivery notes, and possible queries about having parcels left with a neighbour, or a supposedly 'safe location'. Are the seller's part of the contract completed at that point? The more I ponder, the more questions I have.