Which field is mandatory for a non-unique identifier inquiry when searching for a missing person?

In a non-unique identifier inquiry when searching for a missing person, the physical description of the subject is mandatory because it provides essential details that help distinguish the individual being searched for among the larger population. Unlike unique identifiers such as a Social Security number or driver's license number, a missing person's inquiry often relies on descriptive characteristics, such as height, weight, hair color, and other distinctive features. These attributes are crucial in ensuring that the inquiry yields relevant matches from the database, as they help law enforcement and agencies accurately identify the subject.

While the name of the subject, last known address, and subject's age might provide helpful context for the inquiry, the physical description is vital for narrowing down possible matches, especially when there may be multiple individuals with the same name or similar profiles.