It's about the intention.<p>In Civil Law jurisdictions (like the Netherlands) the intention is a very important part of a contract. It's like a secret: laymen think they have to read the contract carefully and not to believe the promises. Mostly this is true because of difficulties of proof. It is often impossible to claim intentions after the fact.<p>However if you have proof (for example countersigned own notes), the judge doesn't have qualms to change the contract wording to conform to intentions. I am studying law, and one old famous case in Germany of the twenties last century has been presented in private contract law: There was a mutual agreement to buy whale meat from Norway. In the contract it was about «Haakjöringsköd». However this was a mutual misunderstanding. Haakjöringsköd is shark meat. The judge decided that the contract is about whale meat, not shark meat.<p><a href="https://de.wikipedia.org/wiki/Haakj%C3%B6ringsk%C3%B6d-Fall" rel="nofollow">https://de.wikipedia.org/wiki/Haakj%C3%B6ringsk%C3%B6d-Fall</a> (German)