Most people agree on what is and is not a street sign—computers not so much. According to a recent Financial Times article, companies working on self-driving cars need hundreds or thousands of employees to manually train computers to tell what a street sign is (something to keep in mind the next time a website asks you to prove that you’re not a computer by selecting every image with a street sign or a car—you’re not only proving that you’re not a computer, you’re training one).

Transactional law doesn’t garner the same level of agreement as street signs. Pick any two contract drafting guides, and you may get two conflicting recommendations on even simple words and phrases, for example: will (Garner: use to create an obligation; Adams & Cramer: use only to show future time), must (Kuney: OK for creating an obligation; Temple-Smith & Cupples: use to create a condition), and may not (Espenschied: use to create a prohibition; Adams & Cramer: do not use).