Node:spacing-interface, Next:spacing-spanner-interface, Previous:spaceable-grob-interface, Up:Graphical Object Interfaces
Something to do with line breaking and spacing. Kill this one after determining line breaks.
This grob interface is used in the following graphical objects: StaffSpacing, SpacingSpanner, SeparationItem, SeparatingGroupSpanner and NoteSpacing
This page is for LilyPond-2.0.0 (stable-branch).