Gregorian chant
Gregorian chant is often coded using four line staffs
(see section ) and using special notes (called neumes)
which are described in section . But the gregorian chant also
needs a special alto clef which is in fact the ancester of the modern
alto clef. The gregorian alto clef can be invoked instead of the
modern one by re-declaring the
normalshapemediumseriesnormalshapemediumseries\clefdutr macro. Thus
\def\clefdutiv{\gclefdut}
will cause the instrument number 4 (i.e. iv) to exhibit a gregorian C
clef whenever the value of \cleftoskiv
refers to an alto clef.
The modern alto clef can be restored for that instrument by :
\def\clefdutiv{\clefdutsymbol}