public static boolean isXML11NameHighSurrogate(int c) {
        return (0xD800 <= c && c <= 0xDB7F);
    }
Returns whether the given character is a valid
high surrogate for a name character. This includes
all high surrogates for characters [0x10000-0xEFFFF].
In other words everything excluding planes 15 and 16.

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