Left panel: [O iii] λ5007/Hβ vs. [N ii] λ6583/Hα diagnostic diagram for the ~7000 ionized regions described in the text. The contours show the density distribution of these regions with the diagram plane, with the outermost contour enclosing 95% of the regions, and each consecutive one enclosing 20% less regions. The color indicates the portion of young stellar populations in the underlying continuum. Central panel: same diagnostic diagram, restricted to those ionized regions with less than a 20% of young stellar population (~1800 regions). Right panel: same diagnostic diagram, restricted to those ionized regions with more than a 20% of young stellar population (~5800 regions). In all the panels, the solid and dashed lines represent the Kauffmann et al. (2003) and Kewley et al. (2001) demarcation curves, respectively. They are usually invoked to distinguish between classical star-forming objects (below the solid line), and AGN powered sources (above the dashed line). Regions between both lines are considered intermediate ones.