addToSet(unknownSet, “abc”);
Because each XML entity not accompanied by external encoding information and not in UTF-8 or UTF-16 encoding must begin with an XML encoding declaration, in which the first characters must be '<?xml', any conforming processor can detect, after two to four octets of input, which of the following cases apply. In reading this list, it may help to know that in UCS-4, '<' is " #x0000003C " and '?' is " #x0000003F ", and the Byte Order Mark required of UTF-16 data streams is " #xFEFF ". The notation ## is used to denote any byte value except that two consecutive ##s cannot be both 00.