37 U.S.C. § 451 — Definitions

(a) Definitions relating to persons:
(1) "Administering Secretary" means: the Secretary of Defense, for the armed forces^* (including the Coast Guard when it operates as part of the Navy); the Secretary of Homeland Security, for the Coast Guard when it is not operating as part of the Navy; the Secretary of Commerce, for the National Oceanic and Atmospheric Administration; and the Secretary of Health and Human Services, for the Public Health Service.
(2) "Authorized traveler" means anyone allowed travel and transportation allowances for official travel ordered or authorized by the administering Secretary. This includes: a member^* of the uniformed services^*; a member's family member; an escort or attendant traveling with a member, a family member, or a deceased member's remains (or helping dependents who can't travel alone, within a year of the member being unable to accompany them); someone on a military funeral honors detail; an ROTC cadet or midshipman; an applicant (or rejected applicant) for enlistment; someone whose work is directly tied to an official government activity under regulations issued under section 464; and anyone else the administering Secretary decides, under those regulations, deserves travel benefits — specifically for things like transporting survivors to a burial or bringing home a member who died overseas, transporting people to a hospitalized or repatriated member, transporting non-medical attendants, transporting people to Yellow Ribbon Reintegration events, single events the Secretary finds necessary for fairness or an emergency, or moving a member's dependent child to school when the member is stationed outside the continental U.S. (or in Alaska or Hawaii but the school is elsewhere), or moving a dependent to where a member is serving aboard a ship being overhauled, inactivated, or built.
(3) "Family member" of a service member means: a dependent (as section 401(a) defines it); a child (as section 401(b)(1) defines it); a parent (as section 401(b)(2) defines it); a sibling; or a former spouse.

(b) Definitions relating to travel and transportation allowances:
(1) "Official travel" means: duty or business away from a member's assigned location; travel between one permanent duty station and another; travel to a first duty station, or travel upon separation or retirement; local travel in or around a temporary or permanent duty station; or other travel the administering Secretary authorizes or orders.
(2) "Actual and necessary expenses" means expenses a traveler really incurs as a reasonable result of official travel.
(3) "Travel allowances" means daily lodging, meals, and other related expenses, including relocation expenses.
(4) "Transportation allowances" means the cost of temporarily or permanently moving a traveler, their personal property, or both.
(5) "Transportation-, lodging-, or meals-in-kind" means the government providing these directly, at no cost to the traveler.
(6) "Miscellaneous expenses" means authorized extra expenses incurred during official travel, on top of the regular allowances.
(7) "Personal property," for transportation allowances, includes baggage, furniture, household items, clothing, privately owned vehicles, house trailers, mobile homes, and other personal items not otherwise banned by law or by regulations under section 464.
(8) "Relocation allowances" means the costs of moving a member and their dependents between an old and new duty station or other authorized place, including pet quarantine costs.
(9) "Dislocation allowances" means the costs of relocating a member's household because of a change in duty station ordered for the government's convenience, or because of an evacuation.
(10) "Permanent duty assignment location" means either a member's official duty station, or a dependent's residence. If a dependent is a student who doesn't live with the member while at school, the student's own location counts as their permanent duty assignment location.