text/html for xml extensions of XHTML

XHTML may be served through http as "text/html" according to the XHTML


if it conforms to Appendix C on compatibility with older user agents,
as provided in section 5.1.

Section 3.1.2 explains how one may use namespaces to enrich the tagset
in XHTML.  I see no conflict between section 3.1 and Appendix C except
possibly in regard to C.11 (DOM handling).  Clearly, DOM handling must
be subordinate to the question of whether to call the XML parser and if
C.11 was intended to be definitive on the content type issue, then it
is in conflict with section 5, and the document stands with an error.

For a user agent, such as Mozilla (http://www.mozilla.org/), that
houses an xml parser there is the general question of when that parser
should be called for an object served through http, and there is
current controversy needing resolution over the question of whether
the http content type is the correct basis for that decision.

Some assert that any XHTML document with namespace extensions must
be served as "text/xml" and must not be served as "text/html".

This issue was last discussed here in February.  See


A user agent with an xml parser need look no further than the first
instance tag.  Thus, a user agent with an xml parser should call that
parser if any of the following is true:

1.  The instance is served through http as "text/xml".  (Please note,
    however, that

2.  The instance is served through http as "text/html" and any of
    the following is true:

    a.  The instance begins with the string "<?xml" .

    b.  The instance has a string matching the case-sensitive pattern
        "<!DOCTYPE html PUBLIC .*XHTML" before the first document
        instance tag.

    c.  The first document instance tag is an open tag for the element
        "html" (all lower case) with a value specified for the attribute

See also:

   Connolly and Masinter, RFC 2854: "The 'text/html' Media Type"

I note that the proposed recommendation


(review ends on May 7) does not mention content-type.
(And content-type is not really a markup issue.)

Now in the mozilla-mathml discussion we are told that there have been
recent further deliberations on this question at W3C.

Can anyone report definitively?


                                    -- Bill

William F. Hammond                   Dept. of Mathematics & Statistics
518-442-4625                                  The University at Albany
hammond@math.albany.edu                      Albany, NY 12222 (U.S.A.)
http://www.albany.edu/~hammond/                Dept. FAX: 518-442-4731

Never trust an SGML/XML vendor whose web page is not valid HTML.
And always support affirmative action on behalf of the finite places.

Received on Monday, 30 April 2001 17:00:51 UTC