General principles of contractual interpretation:
What were the intentions of the parties? Plain meaning rule (parole evidence rule excludes extrinsic evidence [such as letters correspondence / oral testimony, etc – stuff NOT in the language in the contract. Contract is to be interpreted in its plain meaning. Objective not subjective)
But there are exceptions, such as with words with acquired special meanings, and ambiguities. Recall Carlil where the smoke call co’s subjective intent didn’t matter. They read the offer on face value / objectively to determine its meaning
Other evidentiary matters: prior negotiations are inadmissible. So is subsequent conduct and subjective intent
Specific principles of interpretation: