+This should be used to change the properties of objects which
+occur at the same musical moment, such as the notes within a
+chord. Using @code{\override} would affect all the notes
+within a chord, whereas @code{\tweak} affects just the following
+item in the input stream.
+
+Here's an example. Suppose we wish to change the size of the
+middle note (the E) in a C major chord. Let's first see what
+@code{\once \override} would do:
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=1]
+ <c e g>4
+ \once \override NoteHead #'font-size = #-3
+ <c e g>4
+@end lilypond
+
+We see the override affects @emph{all} the notes in the chord.
+This is because all the notes of a chord occur at the same
+@emph{musical moment}, and the action of @code{\once} is to
+apply the override to all layout objects of the type specified
+which occur at the same musical moment as the @code{\override}
+command itself.
+
+The @code{\tweak} command operates in a different way. It acts
+on the immediately following item in the input stream. However,
+it is effective only on objects which are created directly from
+the input stream, essentially note heads and articulations.
+(Objects such as stems and accidentals are created later and
+cannot be tweaked in this way). Furthermore, when it is applied
+to note heads these must be within a chord, i.e., within single
+angle brackets, so to tweak a single note the @code{\tweak}
+command must be placed inside single angle brackets with the
+note.
+
+So to return to our example, the size of the middle note of
+a chord would be changed in this way:
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=1]
+ <c e g>4
+ <c \tweak #'font-size #-3 e g>4
+@end lilypond
+
+Note that the syntax of @code{\tweak} is different from that
+of the @code{\override} command. Neither the context nor the
+layout object should be specified; in fact, it would generate
+an error to do so. These are both implied by the following
+item in the input stream. So the general syntax of the
+@code{\tweak} command is simply:
+
+@example
+\tweak #'@emph{layout_property} = #@emph{value}
+@end example
+
+A @code{\tweak} command can also be used to modify just one in
+a series of articulations, as shown here:
+
+@lilypond[quote,fragment,ragged-right,verbatim,relative=2]
+a ^Black
+ -\tweak #'color #red ^Red
+ -\tweak #'color #green _Green
+@end lilypond
+
+Note that the @code{\tweak} command must be preceded by an
+articulation mark as if it were an articulation itself.
+
+You can find more details of the @code{\tweak} command in