•    Extrinsic evidence has no formalities and can’t be admitted for omitted or plain meaning provisions
•    Evidence applicable for vagueness and ambiguity
•    Mahoney
–    Probably hardest to admit in Texas
–    additional adherence to formality of extrinsic evidence rule
•    Russell
–    Extrinsic evidence of dead dog/dead person is admissible but other extrinsic evidence is not
–    Have to judge when apply extrinsic evidence and when not
–    Ascher disagrees with Langbein to get rid of four-corner doctrine
•    Make sure don’t give too many bequests as to erase residuary