Scatter plot of I([CII]) versus I([NII]) integrated intensities calculated for increasingly larger radial velocity ranges from −40 to −25 km s⁻¹, −50 to −15 km s⁻¹, −60 to −5 km s⁻¹, −70 to +5 km s⁻¹, −80 to +15 km s⁻¹, and −90 to +25 km s⁻¹ (corresponding to I([CII])_i versus I([NII])_i). The I([CII]) versus I([NII]) relationship in Abel (2006) for metallicities 1.0 Z_⊙ and 0.1 Z_⊙ are shown as dashed and dotted straight lines in each panel. As the radial velocity range increases, the bulk of the data points move along the Abel (2006) prediction scale for the [CII] emission contribution of H II regions.