Schematic representation of the two main classes of ETGs, as defined in P13. The EW(Hα) profiles of type i ETGs (blue), such as NGC 1167, show in their extranuclear component (beyond the radius range depicted by the vertical shaded area; typically ~2 kpc in our sample) nearly constant values within the narrow range between EW and EW (green horizontal strip), with a mean value of typically ~1 Å. A few of these systems (labeled i+, blue dashed curve; e.g., NGC 1349) additionally show a steep EW(Hα) increase above EW in their periphery (>1 effective radius), which, as we discuss in Gomes et al. (2015), Gomes et al. (2016; see also Sect. 5.2), is owing to low-level star-forming activity. By contrast, type ii ETGs (red curve) show a centrally very low (≤0.5 Å) mean EW(Hα), increasing smoothly to at their periphery (e.g., NGC 6411). Regarding their nuclear properties, both ETG types display a considerable diversity, from systems with virtually wim-evacuated cores (<0.5 Å) to galaxies hosting a compact central core with an EW(Hα) of a few EW. The profiles in light blue and light red are added to illustrate the spread in the nuclear EW(Hα)s of our sample ETGs.