Accordion register symbols

Accordion register symbols are available as \markup as well as as standalone music events (as register changes tend to occur between actual music events). Bass registers are not overly standardized. The available commands can be found in 'Discant symbols' in the Notation Reference.

\version "2.24.0"

#(use-modules (lily accreg))

\new PianoStaff
<<
  \new Staff \relative {
    \clef treble
    \discant "10"
    r8 s32 f'[ bes f] s e[ a e] s d[ g d] s16 e32[ a]
    <<
      { r16 <f bes> r <e a> r <d g> }
      \\
      { d r a r bes r }
    >> |
    <cis e a>1
  }

  \new Staff \relative {
    \clef treble
    \freeBass "1"
    r8 d'32 s16. c32 s16. bes32 s16. a32[ cis] s16
    \clef bass \stdBass "Master"
    <<
      { r16 <f, bes d>^"b" r <e a c>^"am" r <d g bes>^"gm" |
      <e a cis>1^"a" }
      \\
      { d8_"D" c_"C" bes_"B" | a1_"A" }
    >>
  }
>>