parallel sequences in a period-luminosity-diagram (PLD), to which the authors assigned the letters A to E. SequenceC was explained consisting of stars that pulsate in fundamental mode. Long-period variables on sequenceB were explained as first and second overtone pulsators, and stars on sequenceA as higher overtone variables. Later publications of period-luminosity relations (PLRs) of the LMC revealed that sequenceB actually splits into two separate sequences, namely B and C$^{\prime}$ (see Kiss & Bedding [@kiss]; Ita et al. [@ita]). Meanwhile, different authors (e.g. Fraser et al. [@fraser]; Soszyński et al. [@soszy_a]) are using different labels in a PLD; we use the original labelling of Wood et al. ([@woodb]) plus the additional sequenceC$^{\prime}$. For stars belonging to sequences E or D the variability cannot be attributed to radial pulsation. Stars on sequenceE are thought to be related to close binary systems showing ellipsoidal variability (see Soszyńsky et al. [@soszy_b]). Recently, Nicholls et al. ([@nich]) confirmed this assumption by comparing the phased light and radial velocity curves of LMC red giant binaries. The results of this study also demonstrated that the variations of stars on sequenceE and D are caused by different mechanisms. The LPVs on sequence D show periodicites on two time 