B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
B42D15/00—Printed matter of special format or style not otherwise provided for
B42D15/02—Postcards; Greeting, menu, business or like cards; Letter cards or letter-sheets
B42D15/04—Foldable or multi-part cards or sheets
B42D15/08—Letter-cards or letter-sheets, i.e. cards or sheets each of which is to be folded with the message inside and to serve as its own envelope for mailing