Issue 4908/7: Add Changes entry for \header expressions

[lilypond.git] / Documentation / changes.tely

diff --git a/Documentation/changes.tely b/Documentation/changes.tely
index 647bdb817783fca78100d8f10baa45e6ebf89158..fb1a77f6331bf83b72dc992a31a1bf3a05c7ecdc 100644 (file)
--- a/Documentation/changes.tely
+++ b/Documentation/changes.tely
@@ -61,6 +61,53 @@ which scares away people.
 
 @end ignore
 
+@item
+Blocks introduced with @code{\header} can be stored in variables
+and used as arguments to music and scheme functions and as the
+body of @code{#@{@dots{}#@}} constructs.  They are represented as
+a Guile module.
+
+While @code{\book}, @code{\bookpart}, @code{\score}, @code{\with},
+@code{\layout}, @code{\midi}, @code{\paper} blocks can be passed
+around in similar manner, they are represented by different data
+types.
+
+@item
+Dot-separated symbol lists like @code{FretBoard.stencil} were
+already supported as of version@tie{}2.18.  They may now also
+contain unsigned integers, and may alternatively be separated by
+commata.  This allows usage such as
+@lilypond[quote,verbatim]
+{ \time 2,2,1 5/8  g'8 8 8 8 8 }
+@end lilypond
+and
+@example
+\tagGroup violin,oboe,bassoon
+@end example
+
+@item
+Such lists may also be used in expressions for assignments, sets,
+and overrides.  This allows usage such as
+@lilypond[quote,verbatim]
+{ \unset Timing.beamExceptions
+  \set Timing.beatStructure = 1,2,1
+  g'8 8 8 8 8 8 8 8 }
+@end lilypond
+
+@item
+Association list elements could previously be assigned values
+individually (for example, paper variables like
+@code{system-system-spacing.basic-distance}).  They may now be
+also referenced in this manner, as with
+@example
+\paper @{
+  \void \displayScheme \system-system-spacing.basic-distance
+@}
+@end example
+
+In combination with the previously mentioned changes, this allows
+setting and referencing pseudovariables like @code{violin.1}.
+
 @item
 LilyPond source files may now be embedded inside the generated PDF files.
 This experimental feature is disabled by default and may be regarded as unsafe,