Test #1. This works fine:
$txt0="RRR";
echo ' <a href="?f=3" id="nu'.$var0.'" onclick="func1('.$id0.', '.$id0.');">';
Test #2. This does NOT work, "Done, but with errors on page":
$txt0="RRR";
echo ' <a href="?f=3" id="nu'.$var0.'" onclick="func1('.$id0.', '.$txt0.');">';
THE IMPORTANT THING...