 No evidence to prove the terms maybe given save the document itself (or, if it is lost, secondary evidence of its contents), nor may the contents of the document be contradicted, altered, added to or varied by parol or oral evidence, relating to what passed between the parties either before the written instrument was made or during its preparation.Where the parties have decided that a contract should be recorded in writing, their decision must be respected and the resulting document accepted as the sole evidence of the terms of the contract.The document itself, in other words, discloses the obligations.