Left panel in four rows show the histogram plots of the full-width-half-maximum (FWHM) of the C¹⁸O (2–1) line components for the W43-MM1, G333.60, G338.93, and W51-E protoclusters respectively. Here the blue dashed line denotes the FWHM value of 5.0 km s⁻¹, above which we consider the components have large wing-like structures. Right panel in four rows show the histogram plots of the components for the four protoclusters whose FWHM are above 5.0 km s⁻¹ and intensity peaks (I_peak) are above 3× min_value (blue color) and below 3× min_value (red color).