-Making sheet music may seem trivial, ``you print 5 lines, and then put
-in the notes at different heights'', but as one learns more of it, the
-opposite turns out to be true. There are two problems when making
-sheet music. First, one has to master music notation: the science of
-knowing which symbols to use when what. Second, one has to master
-music engraving: the art of placing symbols such that they look
-elegant.
-
-Common music notation has its roots in the medieval centuries. In this
-time, monks started to write down hints that indicated how their
-sacred music was sung. These hints, neumes, gradually became simpler,
-and at some point became the note heads. Lines were added to the
-neumes, to indicate a reference pitch, which later became the staff.
-Over many centuries, improvements and extensions were added, while
-other concepts disappeared. For example, the neume notation did not
-have an explicit notion of rhythm, but it did have @emph{custodes},
-symbols at the end of the line to indicate the starting pitch of the
-next line. Mensural notation, a notation where each note head takes a
-fixed amount of time, came into being together with the rise of
-counterpoint in the early renaissance. The graphic language of
-notation is still under development; the innovations of contemporary
-music require still newer and more complex notations.
-
-In summary, common music notation encompasses such a wide scope of
-music inherently is complex: there are many rules, and for every rule
-there are exceptional situations where they do not apply. The result
-is that LilyPond cannot support each and every form of notation in
-existence. Rather, we focus on a specific style and idiom: we take
-inspiration from late-romantic music printed at the beginning of the
-20th century. Most of the contemporary music after that, and most of
-the music going back to 17th century can be written in this
-idiom. That is not a fundamental limit, though. There is support for
-some modern notation like clusters, and older notation, such as white
-mensural and gregorian notation, is being worked on.
-
-The term music engraving derives from the traditional process of
-music printing. Only a few decades ago, sheet music was made by
-cutting and stamping the music into zinc or pewter plates,
-mirrored. The plate would be inked, and the depressions caused by the
-cutting and stamping would hold ink. An image was formed by pressing
-paper to the plate. The stamping and cutting was completely done by
-hand. Making corrections was cumbersome, so engraving had to be done
-correctly in one go. As you can imagine this was a highly specialized
-skill, much more so than the traditional process of printing books.
+
+Printing sheet music consists of two non-trivial tasks. First, one has
+to master music notation: the science of knowing which symbols to use
+for what. Second, one has to master music engraving: the art of
+placing symbols such that the result looks pleasing.
+
+Common music notation is a system of recording music that has evolved
+over the past 1000 years. The form that is now in common use, dates
+from the early renaissance. Although, the basic form (i.e. note heads on a
+5-line staff) has not changed, the details still change to express the
+innovations of contemporary notation. Hence, it encompasses some 500
+years of music. Its applications range from monophonic melodies to
+monstrous counterpoint for large orchestras.
+
+How can we get a grip on such a many-headed beast, and force it into
+the confines of a computer program? Our solution is to make a strict
+distinction between notation, @emph{what} symbols to use, and
+engraving, @emph{where} to put them. Anything related to the second
+question is considered ``engraving'' (i.e. typography).
+
+For tackling the first problem, notation, we have broken up the
+problem into digestible (and programmable) chunks: every type of
+symbol is handled by a separate program module, a so-called plug-in.
+Each plug-in are completely modular and independent, so each can be
+developed and improved separately. When put together, the plug-ins
+can solve the music notation program in cooperation. People that put
+graphics to musical ideas are called copyists or engravers, so by
+analogy, each plug-in is also called @code{engraver}.
+
+In the following example, we see how we start out with a note head
+engraver.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Clef_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ \remove "Staff_symbol_engraver"
+ \consists "Pitch_squash_engraver"
+ }
+
+}
+}
+@end lilypond
+
+Then a @code{Staff_symbol_engraver} adds the staff:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Clef_engraver"
+ \remove "Bar_engraver"
+ \consists "Pitch_squash_engraver"
+ \remove "Time_signature_engraver"
+ }
+
+}
+}
+@end lilypond
+
+ The @code{Clef_engraver} defines a reference point for the staff:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Stem_engraver"
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ }
+
+}
+}
+@end lilypond
+
+And the @code{Stem_engraver} adds stems:
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice
+\paper {
+ \translator { \VoiceContext
+ \remove "Phrasing_slur_engraver"
+ \remove "Slur_engraver"
+ \remove "Script_engraver"
+ \remove "Beam_engraver"
+ \remove "Auto_beam_engraver"
+ }
+ \translator { \StaffContext
+ \remove "Accidental_engraver"
+ \remove "Key_engraver"
+ \remove "Bar_engraver"
+ \remove "Time_signature_engraver"
+ }
+}
+}
+@end lilypond
+
+The @code{Stem_engraver} is notified of any note head coming along.
+Every time one (or more, for a chord) note head(s) is seen, a stem
+object is created, and attached to the note head.
+
+By adding engravers for beams, slurs, accents, accidentals, bar lines,
+time signature, and key signature, we get a complete piece of
+notation.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+
+\score { \topVoice }
+@end lilypond
+
+
+
+This system works well for monophonic music, but what about
+polyphony? In polyphonic notation, many voices can share a staff.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+\score { \context Staff << \topVoice \\ \botVoice >> }
+@end lilypond
+
+In this situation, the accidentals and staff are shared, but the
+stems, slurs, beams, etc. are private to each voice. Hence, engravers
+should be grouped. The engravers for note head, stems, slurs, etc. go
+into a group called ``Voice context,'' while the engravers for key,
+accidental, bar, etc. go into a group called ``Staff context.'' In the
+case of polyphony, a single Staff context contains more than one Voice
+context. In polyphonic notation, many voices can share a staff:
+Similarly, more Staff contexts can be put into a single Score context.
+
+@lilypond[]
+\include "engraver-example.lyinc"
+\score {
+<< \new Staff << \topVoice \\ \botVoice >>
+\new Staff << \pah \\ \hoom >>
+ >>
+}
+@end lilypond
+
+
+
+@node Engraving in LilyPond
+@section Engraving in LilyPond
+
+
+The term music engraving derives from the traditional process of music
+printing. Only a few decades ago, sheet music was made by cutting and
+stamping the music into zinc or pewter plates, in mirror image. The plate
+would be inked, and the depressions caused by the cutting and stamping
+would hold ink. An image was formed by pressing paper to the
+plate. The stamping and cutting was completely done by hand. Making
+corrections was cumbersome, so engraving had to be done correctly in
+one go. Of course, this was a highly specialized skill, much more so
+than the traditional process of printing books.