As said dia-compe, like Weinmann there is a round piece that forms the pivot axis for the 'suicide brake lever'
a screw goes into it , ... inside the lever body the screw that pulls up the band mount .. to hold the brake on the bar.
it goes thru the same piece.. thru across , rather than into the end... back in the day the piece was made shorter
if the end screw wasn't needed.
FWIW Aero levers and Top-mount levers that interrupt the housing,
combine to work well as a brake lever in both positions ,
the un realized goal of those older setups..