merged with the long vowels by the time of Koine Greek. Spelling Many different forms of the Greek alphabet were used for the regional dialects of the Greek language during the Archaic and early Classical periods. The Attic dialect, however, used two forms. The first was the Old Attic alphabet, and the second is the Ionic alphabet, introduced to Athens around the end of the 5th century BC during the archonship of Eucleides. The last is the standard alphabet in modern editions of Ancient Greek texts, and the one used for Classical Attic, standard Koine, and Medieval Greek, finally developing into the alphabet used for Modern Greek. Consonant spelling Most double consonants are written using double letters: represent or . The geminate versions of the aspirated stops are written with the digraphs , and geminate is written as , since represents in the standard orthography of Ancient Greek. () ('offspring'), occasionally in inscriptions ('inborn') () was written with sigma . The clusters were written as in the Old Attic alphabet, but as in the standard Ionic alphabet. Voiceless is usually written with the spiritus asper as and transcribed as rh in Latin. The same orthography is sometimes encountered when is geminated, as in , sometimes written , giving rise to the transliteration rrh. Vowel spelling The close front rounded vowels and (an evolution of and respectively) are both represented in writing by the letter upsilon () irrespective of length. In Classical Attic, the spellings and represented respectively the vowels and (the latter being an evolution of ), from original diphthongs, compensatory lengthening, or contraction. 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