Conventional dispersion and steric interactions between mesogenic molecules generally promote SmC*, while the interlayer orientational correlation between transverse. molecular dipoles stabilizes anticlinic SmCA*. Ferroelectric and antiferroelectric orders thus produced are frustrated because of the X-Y freedom and the low-energy barrier between them. We can naturally explain not only a series of subphases between SmCA* and SmC* but also the staircase character of SmCalpha* emerging just below SmA by using the Casimir type long-range interaction due to polarization fluctuations, if we take account of the discrete flexoelectric polarization appropriately in addition to the ordinary one.