32 C.F.R. § 935.134 Arm signals.
Title 32 - National Defense
(a) Any person operating a motor vehicle and making a turn or coming to a stop shall signal the turn or stop in accordance with this section. (b) A signal for a turn or stop is made by fully extending the left arm as follows: (1) Left turn—extend left arm horizontally. (2) Right turn—extend left arm upward. (3) Stop or decrease speed—extend left arm downward. (c) A signal light or other device may be used in place of an arm signal prescribed in paragraph (b) of this section if it is visible and intelligible.
Title 32: National Defense
PART 935—WAKE ISLAND CODE
Subpart N—Motor Vehicle Code
§ 935.134 Arm signals.