>it would actually be "\xD\0\xA\0".
Correct! I was wondering why it was "a\0b\0c\0" paired instead of "\0a\0b\0c". But I don't have "\x".

>You should start your file with a byte order marker (BOM), which is the same as a zero-width no-break spaces. It is U+FEFF, which in UTF-16LE is "\xFF\xFE".
I don't know what actually the code is. But I did a little trick by reading the first two bytes of an existing unicode file into a buffer. It was work !.

>By the way, what you could have done is create a Unicode file in Notepad, then use Perl to look at the file and see what it has in it
The first two bytes cannot be read by print(), and hidden in notepad. How do I know it was "\xFF\xFE" ?

Cheers, ^_^