The smallest யாப்பு component: for prosody purposes, every letter is one of 3 kinds by how long it takes to say - குறில், நெடில், or ஒற்று. These 3 kinds combine to form அசை.

Before a poet even thinks about rhythm, every letter in their line has already been silently sorted into one of these 3 categories - the invisible groundwork under every அசை.

குறில், நெடில், ஒற்று.