Editing Chord name exceptions

The property <code>chordNameExceptions</code> stores a list of chord name exceptions to handle cases either not covered or handled incorrectly.

The default chord names used by LilyPond follow the rules as given in Klaus Ignatzek's book “Die Jazzmethode für Klavier&nbsp;1”; the algorithm to convert chords to chord names can be found in file <code>scm/chord-ignatzek-names.scm</code>. Additional rules are given as chord exceptions and stored in the variable <code>ignatzekExceptions</code>, as set up in file <code>ly/chord-modifiers-init.ly</code>.

This snippet modifies these exceptions in three steps.

# Set up some music with chords and associated markup.  By convention, the root (i.e., the lowest note) of each chord should have pitch&nbsp;c.
# Call Scheme function <code>sequential-music-to-chord-exceptions</code> to create a new list of exceptions, then concatenate it with the existing ones. Since <code>ignatzekExceptions</code> is set up with this function’s second parameter set to <code>#t</code> (to ignore the root of the chords), we have to do the same.
# Register the new exception list.

<lilypond version="2.24">
% Step 1: Define music with chords and markup for maj9 and 6(add9).
chExceptionMusic = {
  <c e g b d'>-\markup { \super "maj9" }
  <c e g a d'>-\markup { \super "6(add9)" }
}

% Step 2: Create extended exception list.
chExceptions =
#(append (sequential-music-to-chord-exceptions chExceptionMusic #t)
         ignatzekExceptions)

theMusic = \chordmode {
  g1:maj9 g1:6.9
  % Step 3: Register extended exception list.
  \set chordNameExceptions = #chExceptions
  g1:maj9 g1:6.9
}

\layout {
  ragged-right = ##t 
}

<<
   \new ChordNames \theMusic
   \new Voice \theMusic
>>
</lilypond>

[[Category:Chords]]
[[Category:Scheme]]
[[Category:Specific notation]]
[[Category:Included in the official documentation]]
[[Category:Snippet]]