the vertical edges: @code{(@var{left-height} . @var{right-height})}.")
(edge-text ,pair? "A pair specifying the texts to be set at the
edges: @code{(@var{left-text} . @var{right-text})}.")
+ (elements-filtered ,boolean? "Callback to filter an element list.")
(round-up-exceptions ,list? "A list of pairs where car is the numerator
and cdr the denominator of a moment. Each pair in this list means that
the multi-measure rests of the corresponding length will be rounded up to