From Bob Tennent (e-mail on 2015-12-30):
  Dirk: I suggest you experiment to see whether the 1st argument is 
  sufficient for your purposes with the new pmx and musixtex, or whether 
  other modifications are needed.

Lyrics lines when not from same paragraph don't join neatly.
Problem has been discussed on mailing list and Rainer gave
a solution. This still (TeXLive 2013) seems to be a little 
unsatisfactory.

Rest in dot and comma shortcuts gives error at PMX stage.
Not recently (2015-08-04) checked.

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Warning for unbalanced braces in the first line a lyrics paragraph.

