51.3—Types of passports.
(b) Official passport.
An official passport is issued to an official or employee of the U.S. Government traveling abroad to carry out official duties. When authorized by the Department, spouses and family members of such persons may be issued official passports. When authorized by the Department, an official passport may be issued to a U.S. government contractor traveling abroad to carry out official duties on behalf of the U.S. government.
(c) Diplomatic passport.
A diplomatic passport is issued to a Foreign Service officer or to a person having diplomatic status or comparable status because he or she is traveling abroad to carry out diplomatic duties on behalf of the U.S. Government. When authorized by the Department, spouses and family members of such persons may be issued diplomatic passports. When authorized by the Department, a diplomatic passport may be issued to a U.S. Government contractor if the contractor meets the eligibility requirements for a diplomatic passport and the diplomatic passport is necessary to complete his or her mission.
(d) Passport card.
A passport card is issued to a national of the United States on the same basis as a regular passport. It is valid only for departure from and entry to the United States through land and sea ports of entry between the United States and Mexico, Canada, the Caribbean and Bermuda. It is not a globally interoperable international travel document.