An exception to the parol evidence rule allows:

• evidence of oral agreement that merely explains the meaning of written terms without changing the terms.
• evidence of oral agreements made on contracts that qualify for mandatory arbitration.
• evidence of oral agreements made on contracts that qualify for court-annexed mediation.
• evidence of oral agreements made at the time of or prior to a written contract that changes the meaning of written terms.
• evidence of oral agreements that are designed to favor the party that drafts a contract.