@layer(optional)Identifies the layer to which a feature applies.
@staff(optional)Signifies the staff on which a notated event occurs or to which a control event
applies. Mandatory when applicable.
@tstamp(optional)Encodes the onset time in terms of musical time, i.e., beats[.fractional beat part],
as expressed in the written time signature.
@width(optional)Measurement of the horizontal dimension of an entity.