A logical outgrowth of the rhythmic modes (fixed patterns of triple rhythms) that governed most late medieval polyphony, isorhythm first appeared in 13th-century motets, primarily in cantus firmus or tenor parts but occasionally in other voices as well.
An example of this could be found among the Maguindanao where the word binalig is used by contemporary musicians as a name for one of the rhythmic modes associated with kangungudan but it has also been used as a term designating a "new" style.
A typical performance consists of alternating sections of composed and improvised material, the composed portions being accompanied by percussion instruments beating one of a number of standard patterns that articulate the rhythmic mode.
The patterns players use are normally considered freer than either the babendil or the dabakan; players could manipulate the patterns freely as long as they conform, reaffirm, reinforce and even generate the rhythmic mode of the piece.
Indications above each song in the "Book of Songs" show the mode, the type of third (major, minor, or neutral), and often the rhythmic mode.
Among the Maguindanao, the rhythmic modes of duyog and sinulog a kamamatuan allowed agung players to serenade the young, unmarried women on the kulintang.
The 13th-century musicians often varied the rhythmic modes by combining several of them simultaneously in different parts of polyphonic composition.
In olden style of play, strictly done by women, the patterns used function to feature/highlight/reinforce the rhythmic modes already established by the singular babendil and dabakan.
The kulintang player's ability to improvise within the parameters of a rhythmic mode is a must.
In fact, though the Maguindanao, Maranao and Tausug artists technically have no concept of scale (because emphasis placed on the concept of "rhythmic modes"), the Pelog and Slendro scales of Java were found to be most satisfactory to their own varying pentatonic/heptatonic scales.
