+@c {{{2 Gregorian accidentals and key signatures
+@node Gregorian accidentals and key signatures
+@unnumberedsubsubsec Gregorian accidentals and key signatures
+
+@cindex accidentals
+@cindex key signature
+
+Accidentals for the three different Gregorian styles are available:
+
+@lilypond[quote,ragged-right,staffsize=26]
+\score {
+{
+ \textLengthOn
+ s^\markup {
+ \column {
+ "vaticana"
+ \line { " " \musicglyph #"accidentals.vaticana-1"
+ " " \musicglyph #"accidentals.vaticana0" }
+ }
+ \column {
+ "medicaea"
+ \line { " " \musicglyph #"accidentals.medicaea-1" }
+ }
+ \column {
+ "hufnagel"
+ \line { " " \musicglyph #"accidentals.hufnagel-1" }
+ }
+ }
+}
+\layout {
+ interscoreline = 1
+ \context { \Score \remove "Bar_number_engraver" }
+ \context { \Staff
+ \remove "Clef_engraver"
+ \remove "Key_engraver"
+ \remove "Time_signature_engraver"
+ \remove "Staff_symbol_engraver"
+ \override VerticalAxisGroup #'minimum-Y-extent = ##f
+ }
+ }
+}
+@end lilypond
+
+As shown, not all accidentals are supported by each style. When
+trying to access an unsupported accidental, LilyPond will switch to a
+different style.
+
+@c @lilypondfile[verbatim,lilyquote,texidoc,doctitle]
+@c {ancient-accidentals.ly}
+
+The style for accidentals and key signatures is controlled by the
+@code{glyph-name-alist} property of the grobs @rinternals{Accidental} and
+@rinternals{KeySignature}, respectively; e.g.:
+
+@code{\override Staff.Accidental #'glyph-name-alist =
+#alteration-mensural-glyph-name-alist}
+
+
+@seealso
+Notation Reference: @ref{Pitches}, @ref{Accidentals}, and
+@ref{Automatic accidentals} give a general introduction of the use of
+accidentals. @ref{Key signature} gives a general introduction of
+the use of key signatures.
+
+Internals Reference: @rinternals{KeySignature}.
+
+