Pic taken at Tirta Empul, Bali. Everyone dressed for a upacara (ceremony).
Essential components: kamen (sarong) generally ikat or batik, kebaya (lace jacket) and selendang (outer sash for kebaya, also generally the minimum requirement for entering a temple). The sabuk is a long broad cloth wound from the hips and around the torso over which the kebaya is worn. Also keeps the kamen in place. I think this has been replaced by a tube top these days though there must be some additional means for securing the kamen.
Ritual cloth is everywhere in Bali. Along with Indonesian terms for clothing like kain you also chance upon wastra (Sanskrit) and dastar (Persian) now and then.