Normalised fluxes plotted with φ (shifted upwards) of two forbidden [N ii] (left-hand panels) and two [Fe ii] (right-hand panels) emission lines in MWC 314. The FWHM ≃ 50  km   s^-1 of the double-peaked [Fe ii] emission lines is comparable to the permitted Fe ii emission lines (see Fig. 16), indicating a common line formation region in a circumbinary disc. The [N ii] lines show smaller FWHM ≃ 25  km   s^-1.