High tone is indicated by an acute accent: á é ɛ́ í ɩ́ ó ɔ́ ú ʊ́, no accent indicates low tone. Long vowels are indicated by doubling the letter: aa ee ɛɛ ii ɩɩ oo ɔɔ uu ʊʊ, both are accented if the tone is high: (áá etc.), only the first is accented if the tone is descending (áa), only the second is accented if the tone is ascending (aá).