A patent ambiguity cannot be cleared up by extrinsic evidence.

Explanation

Where the ambiguity is apparent on the face of the instrument itself, the defect must be cured by the instrument's own language or not at all; outside evidence is inadmissible.

Where this applies

• The document is ambiguous on its face and outside evidence can't fix it.
• The confusion is right there in the text and no external proof can cure it.
• When the ambiguity is obvious from reading the instrument itself, extrinsic evidence is not admissible.

See also

• 10.2.10 From the words of the law there must be no departure.
• 10.3.4 A latent ambiguity may be supplied by proof; for what arises in ambiguity from an extrinsic fact is removed by proof of the fact.