+ This is mainly useful for writing music functions that need to
+ have some property changed just for the duration of the function.
+
+ * `\tag', `\removeWithTag', and `\keepWithTag' can now accept a list
+ of symbols rather than just a single symbol for marking, removing,
+ and keeping music with any of multiple tags. This is particularly
+ important for `\keepWithTag' since one cannot achieve the same
+ effect by using multiple consecutive `\keepWithTag' commands.
+
+ * The `-d old-relative' option has been removed. Not actually
+ accessible from the command line any more, its remaining use was
+ for interpretating `\relative' in LilyPond files converted
+ automatically from version 1.8 or older. It is unclear how much
+ of this was actually still operative.
+
+ * The meaning of `instrumentTransposition' has been reversed. After
+ \set instrumentTransposition = #{ b #}
+ a written `c'' now sounds like `b'. Previously, this would have
+ been the other way round. This and the following change should
+ make dealing with transposing instruments more straightforward.
+
+ * The music generated by `\set' and `\override' commands is no
+ longer affected by `\transpose'. The main consequence is that
+ `\transpose' will transpose audible/concert pitch and printed
+ pitch by the same amount even when the transposed music contains
+ `\transposition'. Previously,
+ \transpose c' f' \transposition bes'
+ was equivalent to `\transposition f''. Now it stays equivalent to
+ `\transposition bes''.
+
+ * When checking for collisions, LilyPond no longer treats objects as
+ rectangles. Instead, the actual shape of objects is approximated
+ using an integral-like approach. This generally results in more
+ even and snug positioning of objects and systems:
+
+ [image of music]
+
+ Previously, the above snippet looked like this:
+
+ [image of music]
+
+ Affected objects include `Accidentals', `Beams', `Clefs',
+ `Dynamics', `FiguredBass', `Flags', `Glissandos', `Lyrics',
+ `MetronomeMarks', `OttavaBrackets', `Pedals', `RehearsalMarks',
+ `Rests', `Scripts', `TextScripts', `Ties', `Tuplets' and
+ `VoltaBrackets'.
+
+ * Tuplets are now created with the `\tuplet' command, which takes a
+ fraction `T/N' to specify that T notes are played in the time
+ usually allowed for N. One `\tuplet' command can create several
+ tuplet groups if their duration is typed after the fraction.
+
+ \tuplet 3/2 { c8 d e } \tuplet 3/2 { f e d } c2
+ \tuplet 3/2 4 { c8 d e f e d } c2