% example one
% gregorian accidentals

\version "2.17.7"

\include "gregorian.ly"

\score { % so-so: there is a collision
  \new VaticanaVoice {
   \[ f  \pes g a \virga bes \]
  }
}

% now we add a previous note
\score { % very wrong: flat at the opposite side
  \new VaticanaVoice  {
    d \[ f \pes g a \virga bes \]
  }
}

% now we split the four notes in two neumae
\score { % also wrong
  \new VaticanaVoice  {
    d \[ f \pes g \]
    \[ a \virga bes \]
  }
}