What is a Remainder Mark?
"Remainder marks" have varied over the years, but today most remainders are marked with a stroke with a felt-tipped marker across the top or bottom of the book's pages, near the spine.
Examples of Remainder Marks on Books
For Audiobooks & DVDs that have remainder marks, most will have a visible "scratch" mark or cut through the products shrink wrap and will usually have some sort of colored marking from a felt pen.
Examples of Remainder Marks on Audiobooks