ΔRV_max distributions of different types of hot subdwarfs. Left panels: Absolute numbers in each bin. Right panels: Normalized fractions in the same bin as in the left panels. The solid black, dotted red, dash-dotted green, and dashed blue lines in the upper panels represent the ΔRV_max distributions for single-lined sdB, sdOB, sdO, and He-rich hot subdwarfs. The same types of lines in the bottom panels show the ΔRV_max distributions of composite sdB, sdOB, sdO, and He-rich hot subdwarfs, respectively.