49 C.F.R. § 236.702 Arm, semaphore.
Title 49 - Transportation
The part of a semaphore signal displaying an aspect. It consists of a blade fastened to a spectacle.
Title 49: Transportation
PART 236—RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES
Subpart G—Definitions
§ 236.702 Arm, semaphore.