+(grob-property-description 'y-offset number? "extra vertical offset
+for ties away from the center line.")
+(grob-property-description 'zigzag-length number? "The length of the
+lines of a zigzag - relative to zigzag-width. a value of 1
+gives 60-degree zigzags.")
+(grob-property-description 'zigzag-width number? "the width of one
+zigzag-squiggle, measured in staff space. The width will be adjusted
+so that the line can be constructed from a whole number of squiggles.")
+