The term “necessary expenses”, with respect to limits on domestic and foreign travel by Members and staff of the Senate, means reasonable expenses for food, lodging, or transportation which are incurred by a Member, officer, or employee of the Senate in connection with services provided to (or participation in an event sponsored by) the organization which provides reimbursement for such expenses or which provides the food, lodging, or transportation directly. Necessary expenses do not include the provision of food, lodging, or transportation, or the payment for such expenses, for a continuous period in excess of 3 days exclusive of travel time within the United States or 7 days exclusive of travel time outside of the United States unless such travel is approved by the Committee on Ethics as necessary for participation in a conference, seminar, meeting or similar matter. Necessary expenses do not include the provision of food, lodging, or transportation, or the payment for such expenses, for anyone accompanying a Member, officer, or employee of the Senate, other than the spouse or child of such Member, officer, or employee of the Senate or one Senate employee acting as an aide to a Member.
2 USC § 4725(b)
None identified, default scope is assumed to be the parent (subchapter III) of this section.