How many ways express session closure?

Hi,

RFC 3080 section 2.4 page 26 example does not include the number
attribute.
Yet the text indicates otherwise:

   When a BEEP peer wants to release the BEEP session, it sends a
   "close" element with a zero-valued "number" attribute on channel
   zero.  The other BEEP peer indicates its willingness by sending an
   "ok" element in a positive reply, e.g.,

       C: MSG 0 1 . 52 60
       C: Content-Type: application/beep+xml
       C:
       C: <close code='200' />
       C: END

So what should it be? 

I looked at two C source implementations that expect the number
attribute.
Sorry if this is a duplicate but I didn't see a prior discussion in this
list.

Thanks,
Mike MacFaden
Kazeon Systems, Inc