 NATO uses the regular English numeric words (Zero, One, with some alternative pronunciations), whereas the ITU (beginning on 1 April 1969) and the IMO define compound numeric words (Nadazero, Unaone, Bissotwo…).In practice these are used very rarely, as they frequently result in confusion between speakers of different languages.A spelling alphabet is used to spell parts of a message containing letters and numbers to avoid confusion, because many letters sound similar, for instance "n" and "m" or "f" and "s"; the potential for confusion increases if static or other interference is present.