public static boolean isXML11Content(int c) {
        return (c < 0x10000 && (XML11CHARS[c] & MASK_XML11_CONTENT) != 0) ||
                (0x10000 <= c && c <= 0x10FFFF);
    }
Returns true if the specified character can be considered
content in an external parsed entity.

@param c The character to check.
stroom-util/src/main/java/stroom/util/xml/XML11Char.java