"a. This flag is for the use of diplomatic officers other than the chief of mission.
b. The design consists of a blue background bearing encircled by 13 blue stars set in the center.
c. This flag may be used for automobile display only."
Notwithstanding sub-paragraph "c" above, the same volume of the FAM tells us both:
2 FAM 155.6 Interior Display of Flags at Foreign
2 FAM 155.6-1 Office of Principal Officer
a. The U.S. flag is displayed at a mission with the Foreign Service flag of the chief of mission, and at a consular office with the flag for consular officers. The U.S. flag is displayed on a staff to the right (officer's right) of the desk of the principal officer, and the Foreign Service flag on a staff of equal height to the left of the desk.
b. At combined posts, the U.S. flag and the flag for consular officers may be displayed in the office of the officer in charge of the consular section.
2 FAM 155.6-3 Consular Office’s Public Waiting Room
Display the U.S. flag and the consular officer flag on staffs of equal height in the main public waiting-room area at a consular post. Display the U.S. flag at the right (waiting audience's right) front of the room as determined by the arrangement of waiting-room seating facilities, and the consular flag to the left front of the room.