((a)) The official having administrative control of an appropriation available to the legislative branch, the judicial branch, the United States International Trade Commission, or the District of Columbia government, and, subject to the approval of the President, the head of each executive agency (except the Commission) shall prescribe by regulation a system of administrative control not inconsistent with accounting procedures prescribed under law. The system shall be designed to—
((1)) restrict obligations or expenditures from each appropriation to the amount of apportionments or reapportionments of the appropriation; and
((2)) enable the official or the head of the executive agency to fix responsibility for an obligation or expenditure exceeding an apportionment or reapportionment.
((b)) To have a simplified system for administratively dividing appropriations, the head of each executive agency (except the Commission) shall work toward the objective of financing each operating unit, at the highest practical level, from not more than one administrative division for each appropriation affecting the unit.