Polyphonic songs

Except staffs of a unique instrument tied together with a big brace, staffs normally begin on the left with a thin vertical rule. However, it is usual to tie all human voices together with a left heavy and right thin vertical rule. This can be specified (but only once per system) by specifying


normalshapemediumseriesnormalshapemediumseries\def normalshapemediumseriesnormalshapemediumseries\lowersonginstrum{ m}

normalshapemediumseriesnormalshapemediumseries\def normalshapemediumseriesnormalshapemediumseries\uppersonginstrum{ n}


where m and n are the intrument numbers of the first and last choral voices. An example of using this feature is given in normalshapemediumseriesPRAETORI and – more complicated – also in normalshapemediumseriesANGESCAM and normalshapemediumseriesANGESCAO.