Negative Seal - The impression in paper, wax, clay or some other medium made by a stamping device, where the background is colored and the characters and/or the design are left white or un-tinted. The Ottoman Empire after 1841 used Negative Seals with the name of the locality, status of the post office and sometimes with the year the seal was introduced, as cancels on mail; this was the first type of postmark used by the Ottoman Empire.
Newspaper stamp - An impressed or adhesive stamp issued to prepay special rates for the sole purpose of mailing newspapers and periodicals.