Hallo und danke!
Egal in was ich es ändere - es wird immer falsch geöffnet.
<html>
<head>
<script type="text/javascript">
var data = "äöü";
location.href='data:text/csv;charset=ISO-8859-2,' + encodeURIComponent(data);
</script>
</head>
<body>
</body>
</html>
<html>
<head>
<script type="text/javascript">
var data = "äöü";
location.href='data:text/csv;charset=UTF-8,' + encodeURIComponent(data);
</script>
</head>
<body>
</body>
</html>