Javier Ruiz-Alma reported on bug-lilypond here:

http://lists.gnu.org/archive/html/bug-lilypond/2013-02/msg00038.html

as follows:

The LSR for typesetting two opposing fermatas above/below a barline will not produce desired result when voices converge on one staff. Suggest adding a note of this, or better yet, how one could overcome this.

http://lsr.dsi.unimi.it/LSR/Item?id=10

Xavier Scheuer responded with a workaround and asking that the shortcoming give rise to a feature request:

http://lists.gnu.org/archive/html/bug-lilypond/2013-02/msg00041.html

as follows:

I use Neil's "multi-mark-engraver" http://lists.gnu.org/archive/html/lilypond-user/2011-08/msg00157.html and so far I never encountered any side-effect.

%%%% Lily code

% you should include the definition of "multi-mark-engraver" % http://lists.gnu.org/archive/html/lilypond-user/2011-08/msg00157.html

markDown =

(define-music-function (parser location text) (markup?)

(make-music 'MarkEvent 'direction DOWN 'label text))

\layout { \context { \Score \remove "Mark_engraver" \consists #multi-mark-engraver \consists "Tweak_engraver" } }

soprano = { c''2 \change Staff = "lower" d''2 \override Score.RehearsalMark #'break-visibility = #begin-of-line-invisible \mark \markup { \musicglyph #"scripts.ufermata" } } bass = { a'1 \markDown \markup { \musicglyph #"scripts.dfermata" } } \score { \new GrandStaff << \new Staff = "upper" { \soprano } \new Staff = "lower" { \bass } >> \layout { } }

%%%% End of lily code

Cheers, Xavier

PS: I do not think a limitation in a LSR snippet that is AFAIK not part of LilyPond official documentation could qualify as a bug. But adding "multi-mark-engraver" features in LilyPond by default could (should?) be considered as a nice feature request.