History of the Greek alphabet consonant letter, rather than seemingly have two exceptions in spelling. Greek, like Phoenician, made a distinction for vowel length; indeed, Greek had five short vowels and seven long vowels, but only five vowel letters. As in Phoenician, the difference in length was not originally made in writing. However, by the 6th century BC the letter eta (not needed for a consonant in eastern dialects of Greek, which lacked ) came to stand for the long vowel , and a new letter, omega, was developed for long . The provenance of omega is not known, but it is generally assumed to
Greek alphabet alternating right-to-left and left-to-right lines (called "boustrophedon", literally "ox-turning", after the manner of an ox ploughing a field) was common, until in the classical period the left-to-right writing direction became the norm. Individual letter shapes were mirrored depending on the writing direction of the current line. There were initially numerous local (epichoric) variants of the Greek alphabet, which differed in the use and non-use of the additional vowel and consonant symbols and several other features. Epichoric alphabets are commonly divided into four major types according to their different treatments of additional consonant letters for the aspirated consonants (/pʰ, kʰ/) and