That characteristic of a binding that enables the
leaves of the book to lie more or less perfectly
flat when the book is opened in its center. It is
a particularly necessary characteristic for music
scores, books which are to be photocopied, and
books which are to be written in. See:SPRING-BACK (1) .
Lying flat is generally associated with the HOLLOW BACK , which
permits a greater degree of throw up in the spine.