Federal agencies must reserve official parking spaces, in the following order of priority, for—

(a) Official postal vehicles at buildings containing the U.S. Postal Service's mailing operations;

(b) Federally owned vehicles used to apprehend criminals, fight fires and handle other emergencies;

(c) Private vehicles owned by Members of Congress (but not their staffs);

(d) Private vehicles owned by Federal judges (appointed under Article III of the Constitution), which may be parked in those spaces assigned for the use of the Court, with priority for them set by the Administrative Office of the U.S. Courts;

(e) Other Federally owned and leased vehicles, including those in motor pools or assigned for general use;

(f) Service vehicles, vehicles used in child care center operations, and vehicles of patrons and visitors (Federal agencies must allocate parking for disabled visitors whenever an agency's mission requires visitor parking); and

(g) Private vehicles owned by employees, using spaces not needed for official business.

However, in major metropolitan areas, Federal agencies may determine that allocations by zone would make parking more efficient or equitable, taking into account the priority for official parking set forth in this section.