ðæt ɪz tə sˈeɪ, ðɛɹˈɪz "nˈoʊ vˌɛɹɪˈeɪʃən fɹʌm pˈiəɹɪəd tə pˈiəɹɪəd ˈʌðɚ ðɐn æz skˈɛdʒuːld æt ðə tˈaɪm ʌv ˈɪʃuːəns".
That is to say, there is "no variation from period to period other than as scheduled at the time of issuance".