<prompt> Translate the following text to EnglishMfumo wa tatu wa sheria, iliyopitishwa kama sehemu 69 hadi 69c ya kanuni za mazoezi, inatumika kwa maombi ya Huduma ya Posta ya mabadiliko ya kudumu ya uainishaji wa barua ambayo ni ndogo kwa tabia.  <response>: A third set of rules, adopted as sections 69 through 69c of the rules of practice,9 applies to Postal Service requests for permanent mail classification changes that are minor in character. 