Diagnostic line ratio diagrams for the relevant regions of the J1000+0234 system. Bottom left: Standard BPT R3 vs. N2 diagram. The solid curved lines represent the maximum starburst line of Kewley et al. (2001), while the straight dashed line on the lower right-hand side divides AGN from LINERs according to Schawinski et al. (2007). The dotted line is the separation from SF and AGN adapted for high-z galaxies by Scholtz et al. (2023). Bottom center: R3 vs. S2 VO87 diagram. Again, the solid line is from Kewley et al. (2001) and the dotted line is the high-z SF/AGN separation from Scholtz et al. (2023) Bottom right: R3 vs. O1 VO87 diagram. The solid line separates SF from AGN according to Kewley et al. (2001). Top left: He2 vs. N2 diagram. The division line between AGN and SF is taken from Shirazi & Brinchmann (2012).