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Re: Comments on last editor's draft of xml-stylesheet [glazman-1]

From: Daniel Glazman <daniel@glazman.org>
Date: Thu, 01 Apr 2010 06:34:40 +0200
Message-ID: <4BB42260.6020100@glazman.org>
To: "Grosso, Paul" <pgrosso@ptc.com>
Cc: www-xml-stylesheet-comments@w3.org
Le 29/03/10 16:55, Grosso, Paul a écrit :
> Daniel,
>
> Thank you for your comment [1] on the latest Association
> Style Sheets draft [2].
>
> You suggest that:
>
>   in the definition of the 'media' attribute, [the spec]
>   should probably specify that if the 'media' pseudo-attribute
>   is absent then the stylesheet applies to "all" media.
>
> We have tried in this spec to stay away from discussing what
> applications do with the information in this PI.  In fact,
> there are applications beyond browsers--including some SGML/XML
> editors--that make use of the information in this PI and that
> ignore such a PI if the media pseudo-attribute is omitted, and
> there is nothing wrong with that behavior.
>
> The (second) Note in section 2 currently reads:
>
> <quote>
> The details of how conforming xml-stylesheet processors
> exploit the information contained in xml-stylesheet
> processing instructions are out of scope for this document,
> as they may reasonably vary from processor to processor.
> </quote>
>
> but that is somewhat of a misstatement.  We are changing
> that Note to read:
>
> <quote>
> The details of how applications
> exploit the information contained in xml-stylesheet
> processing instructions are out of scope for this document,
> as they may reasonably vary from application to application .
> </quote>
>
> The xml-stylesheet processor does not exploit the information
> in the PI at all; it passes it on to the application which
> decides what to do with it, and what the application does
> with it is out of scope of the Associating Style Sheets
> specification itself.
>
> Please reply (cc-ing www-xml-stylesheet-comments@w3.org) as
> to whether you accept such a resolution of your comment.

I think I don't accept it for the following reasons:

1. I agree 100% that some applications may deal with the media
    pseudo-attribute in a way that entirely differs from how a
    browser handles it. In fact, an editing tool may want to
    completely ignore the media pseudo-attribute, whatever its
    value or even its presence/absence, because otherwise it would be
    impossible for instance to edit on a screen a document made
    only to be printed, or edit on a desktop computer a document
    created for |screen and (max-device-width: 320px)|. So this is not a
    good enough reason to avoid specifying what means the absence of the
    media pseudo-attribute.

2. the document specifies the media pseudo-attribute anyway. If
    you want to entirely leave the processing to the document processor,
    then you should say that the PI has pseudo-attributes defined by
    whatever the document language needs to process the link to the
    stylesheet. The only pseudo-attribute defined by this spec should
    be href then. Possibly the mediatype but I'm not even sure since
    some document languages may decide to authorize only CSS and not
    XLST, why not after all...

3. we have only two stylesheet languages on the web usable with this
    PI and as far as I know, only CSS has the notion of rendering media.
    CSS itself will NOT deal with the specification of the media pseudo
    attribute, obviously. In particular, it must not specify what's
    happening if it's absent. This could belong to the document's
    language. But then the absence or presence of the media pseudo-
    attribute has an unpredictable behaviour from the POV of a filter or
    transformation tool that has no knowledge of that specification.
    Let's imagine I have a XML document conformant to a given schema;
    that XML dialect specifies that the absence of media means media=
    "screen" and we want to transform that document on the fly into
    XHTML. A generic filter is then unable to infer that it should
    create a media="screen" (pseudo-)attribute in the PI or <link>
    element in the XHTML result instead of leaving it unspecified.
    Furthermore, there is wide common practice about the media (pseudo-)
    attribute used in the <link> element and the existing stylesheeet
    PI. Its absence is a synonym to media="all". The current draft
    breaks it.

4. saying the absence of the media pseudo-attribute is a synonym to
    media="all" (please note I am not saying it's a default value)
    does not say anything about how a processor should handle it.
    It is still up to the user agent and is not inconsistent, in my
    opinion, with the spirit of this draft.

While we're at it, I just discovered that, unless I did not understand
the 1st paragraph of section 4, the stylesheet PI remains
usable only at the top of the document. If that's the case, I think
this limitation should be lifted to allow scoped stylesheets. I
recommend taking a look at what HTML5 does on that topic. If you need a
separate message about this to register this comment, please let me
know. Please note that a |scoped| pseudo-attribute may be needed in that
case.
This comment is of course of no value if I misunderstod that section, in
which case I apologize for that.

</Daniel>
--
W3C CSS WG, Co-chair
Received on Thursday, 1 April 2010 04:35:27 GMT

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