using the -W option of vim

Question

Hello, the -w and -W options of vim have theoretically the following effect:

-w {scriptout} All the characters that you type are recorded in the file "scriptout", until you exit Vim. This is useful if you want to create a script file to be used with "vim -s" or ":source!". When the "scriptout" file already exists, new characters are appended. See also |complex-repeat|. {scriptout} cannot start with a digit. {not in Vi}

-W {scriptout} Like -w, but do not append, overwrite an existing file. {not in Vi}

But when I do this, the {scriptout} file will always begin with the following hexadecimal sequence: 80 fd 60

What is this “magic number” for? Under Windows with gvim.exe I cannot replay my scriptout until I have removed those three leading bytes…

Thank you for your answers.