Ribbon marker
Also called Bookmark ribbon, ribbon
A ribbon fixed at the head of the spine, inside the book, used as a bookmark. It is added during binding, most often on a hardback.
In practice
It suits a book read in several sittings or kept for reference: a collection, a guide, a cookbook. It needs to be long enough to show at the foot when laid diagonally across the page. Its colour is chosen with the headband’s; a second ribbon earns its place in a book used at two places at once.