The above information about the usage of the vowel letters applies to the classical orthography of Attic, after Athens took over the orthographic conventions of the Ionic alphabet in 403 BC. In the earlier, traditional Attic orthography there was only a smaller repertoire of vowel symbols: , , , , and . The letters and were still missing. All five vowel symbols could at that stage denote either a long or a short vowel. Moreover, the letters and could respectively denote the long open-mid , the long close-mid and the short mid phonemes . The Ionic alphabet brought the new letters and for the one set of long vowels, and the convention of using the digraph spellings and for the other, leaving simple and to be used only for the short vowels. However, the remaining vowel letters , and continued to be ambiguous between long and short phonemes.