code: public static boolean isXMLValid(final char c) {
          boolean result = (c == '\u0009') //
                  || (c == '\n') //
                  || (c == '\r') //
                  || ((c >= '\u0020') && (c <= '\uD7FF')) //
                  || ((c >= '\uE000') && (c <= '\uFFFD'));
          return result;
      }
docs: <p>
  Checker for XML valid character.
  </p>
  <p>
  The Valid XML char is one of:<br>
  #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
  </p>
  
  @see <a href="http://www.w3.org/TR/REC-xml/#charsets">http://www.w3.org/TR/REC-xml/#charsets</a>
  
  @param c
  The <code>char</code> to test.
  @return <code>true</code> if <code>c</code> is one of:<br>
  #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD].