Spectroscopic diagnostic diagrams for all DR7 emission line galaxies with z < 0.1. Contours represent their iso-densities and are drawn with a common ratio of 2. Dots show the location of the outliers (i.e., objects with a line excess with respect to the median value by a factor of R [O   III]   >  5 (red) or 3 (green) in Fig. 1) limiting to those falling in the AGN in the left diagram, i.e., excluding star-forming and composite galaxies.