This first part is from the end of the Business or Friendship discussion guide:
What's a transaction? What kinds of transactions are there? Is there a difference between a 'transaction' and an 'exchange'? Are transactions always fair?
Exchange is all about equivalence. Both sides are keeping accounts, it's okay for both sides to keep account! Also, the entire relationship can be canceled out, and either party can call an end to it at any time. (paraphrase of) Debt p.103What is the relationship between people in a transaction? Are they equals?