Cumulative distribution for double-periodic LPVs for the sequences in Fig. 25. Each line represents a sequence, which are, from the most populated (top line at  [3.6]  = 16.5 mag) to the less populated (bottom line at  [3.6]  = 16.5 mag): for the first period (top panel): Seq. D, Seq. C, Seq. C′, Seq. E, Seq. B, Seq. A. For the second period (bottom panel): Seq. C′, Seq. D, Seq. B, Seq. C, Seq. E, Seq. A.