Module page 

Breaking vertical lists into pages: \vsplit, the page builder, the output routine and \shipout (TeX: The Program §967–§1028 and §638, with e-TeX’s mark classes and saved discards).

\shipout calls the backend through [crate::typeset::ShipoutHook]; without a hook the built-in DVI writer is used, which is what LuaTeX does in IniTeX mode (\outputmode=0).

Functions

precedes_break

TeX’s precedes_break: whether a glue node after p is a legal breakpoint (LuaTeX node numbering, type(p) < math_node).