The optical spectroscopy of Bi3+ in d10-based post transition metal oxides (i. e. gallates, germanates, antimonates indates, stannates) is reviewed and analyzed in the frame of empirical models. 20 different compounds are examined. From this, a methodology is introduced to identify the preferred doping sites for Bi3+ and predict the intra- or extra-ionic origin of the Bi3+ emission in these systems. Further, the emission process in calcite-structured InBO3:Bi and GaBO3:Bi is reconsidered.