Value of Content-Disposition header:

Content-Disposition: attachment; filename*=iso-8859-1''foo-%c3%a4-%e2%82%ac.html

Test Description:

'attachment', specifying a filename of foo--€.html, using RFC2231 encoded UTF-8, but declaring ISO-8859-1

The octet %82 does not represent a valid ISO-8859-1 code point, so the UA should really ignore the parameter.