Categories and fixed="yes"

["Joe Gregorio" <joe@xxxxxxxxxxxxxx>]

The following issue has came up during the AtomPub interop.
There appears to be no way for a server to signal that it
has an open ended set of categories, as long
as they all stay within the same scheme.

Here from the spec is the definition of the "fixed" attribute:

http://bitworking.org/projects/atom/rfc5023.html#rfc.section.7.2.1.1
"""
  The app:categories element can contain a "fixed" attribute, with a
  value of either "yes" or "no", indicating whether the list of categories
  is a fixed or an open set. The absence of the "fixed" attribute is
  equivalent to the presence of a "fixed" attribute with a value of "no".
"""

Now given the following:

      <categories fixed="yes" scheme="http://example.org/extra-cats/";>
      </categories>

Is it legal to add an entry with the following category:

        <atom:category
          scheme="http://example.org/extra-cats/";
          term="joke" />

I believe the answer is no. On the other hand, given:

      <categories fixed="no" scheme="http://example.org/extra-cats/";>
      </categories>

then I believe it is legal for a client to try to add an entry
with the following category:

        <atom:category
          scheme="http://some-other-scheme-not-listed.example.net";
          term="joke" />

1. Is my reading of the spec correct?
2. Does anyone else see a need for categories
   that are open ended but restricted to a
   given scheme? We do, because this is the
   way Blogger works.

   Thanks,
   -joe

-- 
Joe Gregorio        http://bitworking.org