Proper First Name
This field could also be called Formal First Name or First Name at Birth.
This is the formal given name that would appear in official documents.
If a person's name officially changed during their lifetime, this field should contain their first name at birth — unless their first name was officially changed soon after birth, e.g. with an infant adoption, or if the birth certificate was amended or corrected. You may want to put their first name at death in the Preferred First Name field but that field is not as formal. (See below). Either way, explain the name change in the biographical text.