So far from most of the sheet scores I've read, a2 is used mostly in wood and brass instrument staves, while unis. (and on rarer occasion, tutti) is in string instruments. It is even possible to see ...
In a version of "Overture to Lucio Silla" by Mozart, half of the viola part of the song has half notes with a SINGLE slash through it, but 4 dots on the base part of every not (The circular part). ...
Are there usable free sources for (symphonic) orchestra scores? I'm talking about legal sources for pieces that are now in public domain.