-In musical terminology, a ligature is a coherent graphical symbol that
-represents at least two distinct notes. Ligatures originally appeared
-in the manuscripts of Gregorian chant notation roughly since the 9th
-century as an allusion to the accent symbols of Greek lyric poetry to
-denote ascending or descending sequences of notes. Both, the shape
-and the exact meaning of ligatures changed tremendously during the
-following centuries: In early notation, ligatures were used for
-monophonic tunes (Gregorian chant) and very soon denoted also the way
-of performance in the sense of articulation. With upcoming
-multiphony, the need for a metric system arised, since multiple voices
-of a piece have to be synchronized some way. New notation systems
-were invented that used the manifold shapes of ligatures to now denote
-rhythmical patterns (e.g. black mensural notation, mannered notation,
-ars nova). With the invention of the metric system of the white
-mensural notation, the need for ligatures to denote such patterns
-disappeared. Nevertheless, ligatures were still in use in the
-mensural system for a couple of decades until they finally disappeared
-during the late 16th / early 17th century. Still, ligatures have
-survived in contemporary editions of Gregorian chant such as the
-Editio Vaticana from 1905/08.
-
-@syntax
-
-Syntactically, ligatures are simply enclosed by @code{\[} and
-@code{\]}. Some ligature styles (such as Editio Vaticana) may need
-additional input syntax specific for this particular type of ligature.
-By default, the @internalsref{LigatureBracket} engraver just puts a
-square bracket above the ligature: