Period distributions and Bailey diagrams of our ZTF and DECAM RRLs. Left panels, from top to bottom: period distribution of the RRLs adopted to build the templates in the 𝑔_Zr_Zi_Zz_D bands. The RRab are displayed in red and RRc in blue. The red and blue dashed lines display the period thresholds of the LCTs derived in this work, for RRab and RRc, respectively. Right panels: same as left but for the Bailey diagram (period versus Ampl). Dashed black lines display the loci of the Oosterhoff tracks derived by Fabrizio et al. (2019) and transformed into the 𝑔_Zr_Zi_Zz_D bands using the ratios derived in Appendix D.