Comparison of the GREAT [N II] and [C II] spectral profiles for the six pointings with [N II] observations. The red solid curve shows for both lines the Gaussian fit to the main velocity components as in Fig. 2. For the [N II] spectrum the black curve corresponds to the rms flux while the red dotted curve shows the expected [N II] profile assuming [C II] arises only from the ionized gas, with the uncertainty shown as the gray area (see text). For the [C II] spectrum the red dotted curve and shaded area show the profile of [C II] in the ionized gas calculated using the [N II] rms (i.e., the brightest possible [C II] component arising from the ionized gas).