(break-glyph-function ,procedure? "This function determines the
appearance of a bar line at the line break. It takes a glyph and
break-direction and returns the glyph at a line break.")
+ (break-overshoot ,number-pair? "How much does a broken spanner
+stick out of its bounds?")
(breakable ,boolean? "Can this object appear at a line break,
like clefs and bar lines?")
(c0-position ,integer? "An integer indicating the position of