Line parameters derived from the line fit (dark blue line) for a C¹⁸O line, with the data shown as the black step-plot. The peak velocity and flux (V_peak, F_peak) are self-explanatory. The line width is measured at 10% of the peak height. The blue and red side of the velocity width are used to determine the blue and red velocity, and the corresponding velocity asymmetry as the ratio of the blue/red velocity. The integrated flux is measured starting at 3σ. The blue and red parts of the flux are ratioed to obtain the flux asymmetry. Although the underlying multi-Gaussian fit is highly degenerate (blue, green, and red dotted lines), the line parameters derived (integrated flux, peak velocity and flux, line width, velocity, and flux asymmetries) will be independent of the fit if the final fit reproduces the line adequately.