History of the Greek alphabet only required one. The history here is complicated, but basically "sāmekh" dropped out in certain dialects, and was reused to represent in others, while usage for the sound varied between "ṣādē" and "šin". The letter now known as sigma took its name from "sāmekh" but its form from "šin", while the letter San, which occurred in a few dialects only, took its name from "šin" but its place in the alphabet from "ṣādē". A further Greek letter of uncertain origin, sampi, is found occasionally, and may represent an affricate, such as . For the special case of zeta, see Zeta
History of the Greek alphabet foreshadowed the development of vowel letters with a limited use of "matres lectionis", that is, consonants that pulled double duty as vowels, which for historical reasons occurred mostly at the ends of words. For example, the two letters "wāw" and "yōdh" stood for both the approximant consonants and , and the long vowels and in Phoenician. By this point in time, Greek had lost its sound, so Phoenician "yōdh" was used only for its vocalic value, becoming the Greek vowel letter iota . However, several Greek dialects still had a sound, and here "wāw" was used for both of its