Notes. SDSS sample (n = 353). Columns: (1) CIG number; (2) classification with the [N ii] diagnostic diagram; (3) classification with the [S ii] diagnostic diagram; (4) classification with the [O i] diagnostic diagram; (5) final classification adopted for our study; (6) transition object subtype. Acronyms: SFN – star-forming nucleus; TO – transition object; NLAGN – narrow line AGN (Seyfert 2 or LINER); LINER – LINER; Sy1 – Seyfert 1; Sy2 – Seyfert 2; UNK – unknown (only for the TO subtype). Three galaxies have no unambiguous classification between TO and NLAGN (“TO or NLAGN”) and three more between TO and SFN (“TO or SFN”), as explained in the text. Subtype of transition object if classified as a TO (see text).