(type ,symbol? "The type of this music object. Determines iteration in some cases.")
(types ,list? "The types of this music object; determines by what
engraver this music expression is processed.")
+ (tweaks ,list? "An alist of properties to override in the backend
+-for the grob made of this event.")
(value ,scheme? "Assignment value for a
translation property")
(void ,boolean? "If this property is #t, then the music expression is to be