Escape codes were defined to indicate which national variant applied to a piece of text, but they were rarely used, so it was often impossible to know what variant to work with and, therefore, which character a code represented, and in general, text-processing systems could cope with only one variant anyway.
ɛskˈeɪp kˈoʊdz wɜː dᵻfˈaɪnd tʊ ˈɪndᵻkˌeɪt wˌɪtʃ nˈæʃənəl vˈɛɹiənt ɐplˈaɪd tʊ ɐ pˈiːs ʌv tˈɛkst, bˌʌt ðeɪ wɜː ɹˈɛɹli jˈuːzd, sˌoʊ ɪt wʌz ˈɔfən ɪmpˈɑːsᵻbəl tə nˈoʊ wʌt vˈɛɹiənt tə wˈɜːk wɪð ænd, ðˈɛɹfoːɹ, wˌɪtʃ kˈæɹɪktɚɹ ɐ kˈoʊd ɹˌɛpɹᵻzˈɛntᵻd, ænd ɪn dʒˈɛnɚɹəl, tˈɛkstpɹˈɑːsɛsɪŋ sˈɪstəmz kʊd kˈoʊp wɪð ˈoʊnli wˈʌn vˈɛɹiənt ˈɛnɪwˌeɪ.