[Standards] Questions about xhtml-im

Jehan Jehan.3cptgb at no-mx.jabberforum.org
Thu Jul 17 23:10:05 UTC 2008


I try to understand the logic of 'xhtml-im'
(http://www.xmpp.org/extensions/xep-0071.html). Is there anyone nice
enough to explain me the following points please? :-)

1/ Section 4: > Lightweight text markup is then provided within an <html/> element
> qualified by the 'http://jabber.org/protocol/xhtml-im' namespace. [14]
> However, this <html/> element is used solely as a "wrapper" for the
> XHTML content itself, which content is encapsulated via one or more
> <body/> elements qualified by the 'http://www.w3.org/1999/xhtml'
> namespace, along with appropriate child elements thereof.

So why is the xhtml-im namespace for here if it is not used at all (as
the direct and only son is under the normal html namespace)? This is
maybe a stupid question as I think I have still not understood the
complete logic behing the xml namespaces...

Or should its role be to "tell" (through its schema?) which subset of
xhtml is authorized in it?

Now the real and more important issues I have:

2/ in 6.1, it is said that the structure module includes the elements
<head>, <html> (I guess this "html" means the one under the namespace
'http://www.w3.org/1999/xhtml', not the one under the namespace
'http://jabber.org/protocol/xhtml-im', doesn't it?) and <title>. But in
the meantime, it is said that under the XMPP <html> (prefixed by
'http://jabber.org/protocol/xhtml-im') tag, you have only one or more
<body> ('http://www.w3.org/1999/xhtml').

Yet as far as I know (and as confirmed by any of the 'xhtml DTDs'
(http://www.w3.org/TR/xhtml1/#dtds) ), inside a body
('http://www.w3.org/1999/xhtml'), you cannot have any html
('http://www.w3.org/1999/xhtml'), head or even title tag.

Hence I would think this is an error telling they are possible tags in
the xhtml-im subset of xhtml (as a consequence, it becomes useless to
unrecommend them in the section 7.1!). Or were you planning any other
wrapper element than <html> ('http://jabber.org/protocol/xhtml-im') for
these tags?

3/ Section 6.6, I don't understand what the Style attribute module
> The Style Attribute Module is defined as including the style attribute
> only, as included in the preceding definition tables.

It looks like there is no additional information that what already was
in other modules (which already included the "style" attribute for any
So what is this "module" and its content?

4/ Section 7, I don't understand the concept behind all the
"recommended profile" part. It looks like the whole important idea
behind xhtml-im here is solely style, not semantic! I mean, this is the
whole point of the importance given about "semantic web", and all the
work which has been done for the last years in the W3C to bring real
semantic to xhtml. And in our subset, we would want to remove all this
as not recommended and give higher priority to the absolutely not
semantic part? The main example is that the most important attribute for
all tag seems to be "style"!

And several tags that I would think are very basic and important in a
definition of xhtml-im are not recommended, like "em", or "strong", or
all the titles tag "h1" to "h6", the cite and blockquote, etc.
-> You don't set text in bold or italic (which you can do with the
style attribute), you emphasize them!
-> You don't set a text with a bigger police, underline it and give it
a different police, no you set titles, subtitles, etc.
The style should come from the meaning of the tag, like in the web!

If you read the abstract of the xhtml 1 specif (linked from the XEP
-0071), the semantic is given a nice part:
> This specification defines the Second Edition of XHTML 1.0, a
> reformulation of HTML 4 as an XML 1.0 application, and three DTDs
> corresponding to the ones defined by HTML 4. The semantics of the
> elements and their attributes are defined in the W3C Recommendation for
> HTML 4. These semantics provide the foundation for future extensibility
> of XHTML. Compatibility with existing HTML user agents is possible by
> following a small set of guidelines.

The web is becoming more and more semantic, this would be a shame XMPP,
which is pretty new, would not be semantic...

5/ Linked to the previous point, this XEP seems to describe XMPP usage
only for IM point of view, but it has other usages now:
> Even within the restricted set of modules specified as defining the
> XHTML-IM Integration Set (see preceding section), some elements and
> attributes are inappropriate or unnecessary for the purpose of instant
> messaging

For instance, there can be notifications, textual data exchange, and
most probably other cases... And for this, we may need to structure text
(which then can be rendered according to the given structure!).

6/ In section 12.2, when you explain the meaning of "ignoring" an
element, I can read:
> Therefore, an XHTML-IM implementation MUST process all XHTML 1.0 child
> elements of the XHTML-IM <html/> element even if such child elements are
> not included in the XHTML 1.0 Integration Set defined herein, and MUST
> present to the recipient the XML character data contained in such child
> elements.

I am just asking the meaning of this sentence. What I understand is
that when I encounter a tag which I recognize as being xhtml, but which
is not in the xhtml-im subset, then I must display it "as is"?

Thanks by advance for any answer.


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