((a)) ** .—** This subchapter shall apply with respect to—

((1)) first-class mail letters and sealed parcels;

((2)) first-class mail cards;

((3)) periodicals;

((4)) standard mail;

((5)) single-piece parcel post;

((6)) media mail;

((7)) bound printed matter;

((8)) library mail;

((9)) special services; and

((10)) single-piece international mail,

((b)) ** .—** Mail matter referred to in subsection (a) shall, for purposes of this subchapter, be considered to have the meaning given to such mail matter under the mail classification schedule.