A gatra (“embryo” or “semantic unit”) is a unit of melody in Javanese gamelan music, analogous to a measure in Western music. It is often considered the smallest unit of a gamelan composition. A gatra consists of a sequence of four beats (keteg), which are filled with notes (or rests, pin) from the balungan.In general, the second and fourth beats of a gatra are stronger than the first and …

: https://en.wikipedia.org/wiki/Gatra_(music)