Swiss binding
Also called exposed spine binding
A binding in which the cover, often rigid, is glued only to the back of the last leaf: the spine stays bare, its sewn sections on show, and the book opens flat.
In practice
It suits books read open on a table: catalogues, art books, cookbooks. The bare spine carries no title, which matters on a bookshop shelf, and the sections must be sewn neatly because they show. Ask for a blank dummy: it is the best way to judge how the book opens and how the spine looks before committing.