http://www.unicode.org/Public/3.0-Update/UnicodeData-3.0.0.txt:
>FFFD;REPLACEMENT CHARACTER;So;0;ON;;;;;N;;;;;

For some reason when the above character is in any regex character class it 
causes a RESyntaxException with description 'Bad Character Class'. I attempted 
to use it in the following context:

  private static String XMLescape(String s)
  	throws RESyntaxException
  {
	if (s==null) return s;
	if (s.length() == 0) return s;

	// XML 1.0 standard actually says:
	// Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | 
[#x10000-10FFFF]
	// For some reason this library doesn't like the Unicode character 
\\uFFFD.
	RE r = new RE("[^\\u0009\\u0010\\u0013\\u0020-\\uD7FF\\uE000-\\uFFFC]");

	return r.subst(s, "");
  }

I'm using the JRE Standard Edition 3.0.

Regards,

Tasuki.