My guess would be that Microsoft chose an ASCII encoding for this file rather than a UTF-8 encoding because, at the time, CVS repositories could be very temperamental about file encodings.
For the XML document, that I cited (it seems to be, contributed by Microsoft) from w3c xml schema test suite, as following,
<doc value="؀؁ ......
Why do you say, its encoded with ASCII (is this what you're saying) and not UTF-8?
