“…. The two sections, however, differ in some material particulars. Section 91 applies to all documents, whether they purport to dispose of rights or not, whereas s. 92 applies to documents which can be described as dispositive. Section 91 applies to documents which are both bilateral and unilateral, unlike s. 92 the application of which is confined only to bilateral documents. Section 91 lays down the rule of universal application and is not confined to the executant or executants of the documents. Section 92, on the other hand, applies only between the parties to the instrument or their representatives in interest. There is no doubt that s. 92 does not apply to strangers who are not bound or affected by the terms of the document. Persons other than those who are parties to the document are not precluded from giving extrinsic evidence to contradict, vary, add to or subtract from the terms of the document. It is only where a question arises about the effect of the document as between the parties or their representatives in interest that the rule enunciated by s. 92 about the exclusion of oral agreement can be invoked. This position is made absolutely clear by the provisions of s. 99 itself. Section 99 provides that "persons who are not parties to a document or their representatives in interest, may give evidence of any facts tending to show a contemporaneous agreement varying the terms of the document . ”
