function of type (beam multiplicity dy staff-line-thickness) -> real. Default value: default-beam-y-quants, also available: beam-traditional-y-quants.
.")
(grob-property-description 'visibility-lambda procedure? "a function that takes the break direction and returns a cons of booleans containing (TRANSPARENT . EMPTY).")
+(grob-property-description 'weird number? "urg?")
(grob-property-description 'when moment? "when does this column happen?.")
(grob-property-description 'word-space number? "elongate left by this much (FIXME: cumbersome semantics).")
(grob-property-description 'x-gap number? "horizontal gap between notehead and tie.")