French joint
See
illustration A free-swinging joint
produced by setting the board a slight distance
(approximately 1/8 to 1/4 inch, depending on the
size of the book) away from the backing shoulder.
This type of joint allows thicker covering
material to be used, while still allowing the
covers to open easily. The French joint is one of
the more notable characteristics of library
binding. Also called "open joint." See also: CLOSED JOINT (94 , 335 )