Panel a: B over V amplitude ratios of GGC T2Cs. Black shows T2Cs from NGC 6388 and NGC 6441, and the other symbols have the same meaning as in Figs. 1 and 4. The solid red line denotes the average, and the dotted lines denote the 1σ dispersion. Panel b: I over V amplitude ratios of bulge and ω Cen T2Cs. The red line displays a linear fit. The symbols have the same meaning as in Fig. 5. Panel c: same as in panel b, but for K_s over V amplitude ratios. The red line displays a linear fit for log P <  1.3 and the average for log P >  1.3. Panel d: same as in panel b, but for K_s over I amplitude ratios. The red line displays a linear fit for log P <  1.3 and the average for log P >  1.3.