(bounded-by-me ,ly:grob-array? "list of spanners that have this
column as start/begin point. Only columns that have grobs or act as
bounds are spaced.")
+ (circled-tip ,boolean? "Put a circle at start/end of hairpins (al/del niente)")
(columns ,ly:grob-array? "list of grobs, typically containing
paper-columns or note-column objects.")
(conditional-elements ,ly:grob-array? "Internal use only")