NATO phonetic alphabet by those who exchange voice messages by radio or telephone, regardless of language differences or the quality of the communication channel. The 26 code words in the NATO phonetic alphabet are assigned to the 26 letters of the English alphabet in alphabetical order as follows: , Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, , Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu. Strict adherence to the prescribed spelling words is required in order to avoid the problems of confusion that the spelling alphabet is designed to overcome. As noted in a
History of the International Phonetic Alphabet though the space did not allow the back vowels to appear beneath the velars. A tie bar placed below symbols, as in , was mentioned again. was now attached to the preceding letter, as in . A few illustrations in the chart were changed: was added for rhoticity, and were replaced with . The word "etc." was dropped from the list of tones. The 1999 "Handbook of the International Phonetic Association" was the first book outlining the specifications of the alphabet in 50 years, superseding the 1949 "Principles of the IPA". It consisted of just over 200 pages, four times