Greek alphabet glottal ("heth") was borrowed in two different functions by different dialects of Greek: as a letter for /h/ (Η, heta) by those dialects that had such a sound, and as an additional vowel letter for the long (Η, eta) by those dialects that lacked the consonant. Eventually, a seventh vowel letter for the long (Ω, omega) was introduced. Greek also introduced three new consonant letters for its aspirated plosive sounds and consonant clusters: Φ ("phi") for , Χ ("chi") for and Ψ ("psi") for . In western Greek variants, Χ was instead used for and Ψ for . The origin
NATO phonetic alphabet underlined syllable of each letter word should be emphasized, and each syllable of the code words for the figures (1969–Present) should be equally emphasized. The Radiotelephony Spelling Alphabet is used by the International Civil Aviation Organization for international aircraft communications. The ITU-R Radiotelephony Alphabet is used by the International Maritime Organization for international marine communications. NATO phonetic alphabet The NATO phonetic alphabet, officially denoted as the International Radiotelephony Spelling Alphabet, and also commonly known as the ICAO phonetic alphabet, and in a variation also known officially as the ITU phonetic alphabet and figure code, is the most widely used radiotelephone