<mscgen caption="äöüßÄÖÜ"> msc { Ä,Ö,Ü, ä, ö, ü, ß; ä->ä [label="ä"]; ö->ö [label="ö"]; ü=>ü [label="ü"]; ß=>ß [label="ß"]; Ä=>Ä [label="Ä"]; Ö=>Ö [label="Ö"]; Ü<<=Ü [label="Ü"]; } </mscgen>
This throws an encoding error:
Error detected at line 2: syntax error, unexpected characters. > Ä,Ö,Ü, ä, ö, ü, ß;
The characters are no parsed as UTF-8 but as US-ASCII.
According to the changelog this issue should be fixed in the side of mscgen, so it appears that the MW extension is creating some wrong handling of the characters.