LenderLenderPerson Fannie Mae approved to sell or service Mortgage Loans. due diligence performed for the BorrowerBorrowerPerson who is the obligor per the Note. , Key PrincipalKey PrincipalPerson who controls and/or manages the Borrower or the Property, is critical to the successful operation and management of the Borrower and the Property, and/or may be required to provide a Guaranty. , and PrincipalPrincipalPerson who owns or controls specified interests in the Borrower per Part I, Chapter 3: Borrower, Guarantor, Key Principals, and Principals, Section 303: Key Principals, Principals, and Guarantors. using the ACheck application.