length of the book
A term used by some bookbinders to indicate the
distance between the "X" points of the gathered
sections marked up for sewing by hand. The "X"
points indicate where the head and tail are to be
trimmed, i.e., the "length of the book" being the
distance between the "X" points. It is actually
the height of the text block but not that of the
finished book, unless it is a cut flush binding.