[NII]-based diagnostic diagrams of the parent (gray) and Effelsberg (blue) samples. Demarcation lines were derived by Kewley et al. (2001; dashed) to set an upper limit for the position of star-forming galaxies and by Kauffmann et al. (2003b; three-point dashed) to trace the observed lower left branch (purely star-forming galaxies) more closely. The dividing line between Seyferts and LINERs (long dashed) was set by Schawinski et al. (2007).