Traditional haiku consist of 17 on (also known as morae), in three phrases of 5, 7 and 5 on respectively . Although haiku are often stated to have 17 syllable, it is important to understand that syllables and on are not the same .
1. Lanoue, David G. Issa, Cup-of-tea Poems: Selected Haiku of Kobayashi Issa, Asian Humanities Press, 1991, ISBN 0-89581-874-4 p.8
2. Cor van den Heuvel. The Haiku Anthology, 2nd edition, Simon & Schuster, 1986, ISBN 0-671-62837-2 p.11