XHR suggestion: multipart/form-data formatting methods?

Currently, the XHR specification doesn't include the possibility of
multipart/form-data methods - which can be useful for POST requests.
Typically, the body of a HTTP request contains the data fields - but a
largish field value could be problematic.

Maybe a few additional methods might be handy.  Like a
setBodyValue(name, value) method - or for file uploads,
setBodyFile(name, contents, fileName).  Once these becomes used for a
particular request, then, the send() method call must be with a null
argument.

I'm not going to force this down anyone's throat, though.  It's just a
suggestion.

-- 
"The first step in confirming there is a bug in someone else's work is
confirming there are no bugs in your own."
-- Alexander J. Vincent, June 30, 2001