The line profile parameter P₁₀ = ΔV₁₀/ΔV₉₀ is presented here for a sample of selected sources. Note that this parameter is clearly larger for the broad-based single peaked line profiles. The P₁₀-value is an average of the lower J-transition lines (up to P(14)). The J-transition corresponding to each plotted profile is given in the figure. The narrow absorption line seen toward DoAr24E A is due to ¹³CO absorption in the foreground cloud.