### 4.3.2 Page breaking

The default page breaking may be overridden by inserting \pageBreak or \noPageBreak commands. These commands are analogous to \break and \noBreak. They should be inserted at a bar line. These commands force and forbid a page-break from happening. Of course, the \pageBreak command also forces a line break.

The \pageBreak and \noPageBreak commands may also be inserted at top-level, between scores and top-level markups.

There are also analogous settings to ragged-right and ragged-last which have the same effect on vertical spacing. If ragged-bottom is set to #t the systems will not be justified vertically. When ragged-last-bottom is set to #t, as it is by default, empty space is allowed at the bottom of the final page (or the final page in each \bookpart). See Fixed vertical spacing \paper variables.

Page breaks are computed by the page-breaking function. LilyPond provides three algorithms for computing page breaks, ly:optimal-breaking, ly:page-turn-breaking and ly:minimal-breaking. The default is ly:optimal-breaking, but the value can be changed in the \paper block:

\paper {
page-breaking = #ly:page-turn-breaking
}

When a book has many scores and pages, the page breaking problem may be difficult to solve, requiring large processing time and memory. To ease the page breaking process, \bookpart blocks are used to divide the book into several parts: the page breaking occurs separately on each part. Different page breaking functions may also be used in different book parts.

\bookpart {
subtitle = "Preface"
}
\paper {
%% In a part consisting mostly of text,
%% ly:minimal-breaking may be preferred
page-breaking = #ly:minimal-breaking
}
\markup { … }
…
}
\bookpart {
%% In this part, consisting of music, the default optimal
%% page breaking function is used.
subtitle = "First movement"
}
\score { … }
…
}

#### Predefined commands

\pageBreak, \noPageBreak.