@beam.color(optional)Color of beams, including those associated with tuplets.
Value conforms to data.COLOR.
@beam.rend(optional)Encodes whether a beam is "feathered" and in which direction. Allowed values are: "acc" (Beam lines grow farther apart from left to right.), "rit" (Beam lines grow closer together from left to right.), "norm" (Beam lines are equally-spaced over the entire length of the beam.)
@beam.slope(optional)Records the slope of a beam; e.g., in terms of MEI virtual units. Positive values
indicate upward slope, negative values indicate slope downward, and a zero value indicates
the beam
is horizontal.
Value conforms to data.MEASUREMENTSIGNED.