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Re: My comments on Additional Requirements for Bidi in HTML (20100304 WD)

From: Martin J. Dürst <duerst@it.aoyama.ac.jp>
Date: Mon, 15 Mar 2010 20:18:07 +0900
Message-ID: <4B9E176F.6000703@it.aoyama.ac.jp>
To: public-i18n-bidi@w3.org
I mentioned backwards-compatibility issues in various places. I'd like 
to add that I think in some cases, this can be alleviated by using CSS 
that anticipates the changes.

As an example, part of the 'bdi' functionality may be produced by

*[dir=rtl] > [bdi=bdi]:before { content: "\200F" }
*[dir=rtl] > [bdi=bdi]:after { content: "\200F" }

Of course, that doesn't yet work in all cases, and some things such as 
dir='auto' are difficult to do in CSS only.

Regards,   Martin.

On 2010/03/15 19:57, "Martin J. Dürst" wrote:
> Dear Bidi specialists,
> Here are my comments on Additional Requirements for Bidi in HTML
> (20100304 Working Draft).
> My comments are based on my experience since being involved in designing
> the currently existing bidi provisions for both HTML (originally
> http://tools.ietf.org/html/rfc2070) and CSS, and on research on
> displaying structured documents and data in a bidi context (see
> http://www.sw.it.aoyama.ac.jp/2008/pub/IUC32-bidi/).
> Before I start the actual comments, I want to the current effort is
> really worthwhile. When the current bidi solution for HTML was designed
> (~1995?), we indeed did not think about the details of form fillin or
> composing documents from text snippets e.g. from a database.
> Overall comments:
> I haven't commented on every editorial detail. I think most editorial
> details can be fixed later. However, I think we should make a strong
> effort to make sure that bidi-related terminology is correct and clean,
> because the HTML WG may just take the text from us without changes and
> it's awkward to later go back and tell them to fix it.
> In the introduction, there should be a note saying that familiarity with
> bidi text display and with the Unicode Bidi Algorithm in particular is
> assumed.
> Notation:
> - "uppercase English" -> "uppercase Latin" (this is a script issue, not
> a language issue)
> - "are stored in memory": This is usually called "logical order". Please
> use that term. If felt necessary, let's add explanations in parentheses.
> End of document: Please provide a References section, as usual for W3C
> documents.
> 1.2 Base direction: "is displayed in RTL as" should read "is displayed
> with a base direction of RTL as"
> 1.3 Terminology:
> - Some of the terms here, such as "computed direction", are clearly
> specific to this document, and should be kept. Others (e.g. base
> direction, LRE,...) are taken from other places and should either be
> removed or marked as such (explicitly pointing to their origin). That
> will help a reader skip stuff that's already known, and will help a
> potential HTML editor to know how to incorporate these in the relevant
> document.
> - LRO: "arranges characters from left to right" -> "arranges characters
> strictly from left to right"
> - UBA: "In HTML" -> "In current HTML" or "In HTML 4" or some such.
> Ideally, the document is written in such a way that it can be read
> without confusion in a few years.
> Use of "RTL" in example text: Because this reads "LTR" when displayed,
> it may be very confusing to people not totally familiar with bidi
> issues. I suggest changing the example text to remove this pitfall.
> The explanation of how the various proposals can be implemented based on
> the UBA should be worked out in more detail, to be complete, because
> that's what probably will be used for the definition of the features in
> the new HTML spec. So e.g. not "missing PDFs will be assumed at the
> close of an element" but "add missing PDFs at the end of an element".
> 2.1 bidi isolation of inlines
> The proposal is basically a very good idea. Some details:
> - The name of the new attribute, "bdi", needs more thought. It's too
> close to "bidi" and "bdo", and cryptic. "bidi-isolate" or something
> similar seems way more appropriate.
> - In the work on displaying e.g. XML documents with bidi content, we
> bumped into the 'reverse' of this issue, namely how to make an inline
> element with explicit directionality behave as a single entity of that
> directionality. For that purpose, it's necessary to enclose the element
> in bidi marks (LRM or RLM) of the same directionality as the element
> itself (not of the directionality of the context as in the proposal). It
> may be possible that there are other uses for this in the wild, and that
> this could be added as an additional option for this attribute.
> - There should be a clear specification about what happens when there's
> a 'bdi' attribute without a 'dir' attribute. (nothing? something?)
> - I think there should be some text about deployment. This feature only
> makes sense if all major browsers implement it and it is deployed in a
> large percentage of the user base. There's no "backwards compatibility
> story", unfortunately.
> - "except in special cases indicated in the sections below": Please put
> in pointers to the actual sections.
> 2.2 auto-direction
> I personally think having two options, named 'word-count' and
> 'first-strong', is best (apparently, both are currently in use, so they
> both must have some utility?). I don't think making this the default on
> some elements is a good idea; while that would be appropriate for a
> totally new design, it's not appropriate here because it would increase
> backwards-compatibility problems.
> 2.3 Reporting user direction choice for text input fields
> - Looks like a good idea in general.
> - I don't understand what's meant with "scrips are not available ... in
> e-mail forms"
> 2.4 Image flips
> - I agree with another commenter (sorry, forgot the name) that this
> shouldn't be a general image mirroring feature. In its simplest, it
> could just be a binary property: bidi-mirror: yes/no (assuming the image
> source is LTR), but I understand the desire to also allow RTL source
> images. However, I'd personally take the attribute values the other way
> round, indicating the directionality of the original image, not the
> directionality context in which the image has to be mirrored.
> - This may belong into CSS, not HTML. There should be some warnings
> about deployment (e.g. "for the time, don't use this unless the image is
> still understandable even when displayed the wrong way round").
> - It may be worthwhile to give some though to vertical directionality, too.
> 3.1 <br> as a bidi separator
> - Fixing all those pages that think <br> is a paragraph separator would
> be best!
> - Browsers should definitely converge. As far as this is the job of the
> HTML WG, maybe we can just present two solutions (one like the current
> proposal, another closer to HTML 4, i.e. making bdi='no' the default for
> <br>, too) and have the HTML WG figure out which way browser makers are
> going to converge.
> - With the current proposal, the fact that this ties in with the 'bdi'
> attribute is quite nice.
> - The necessary changes to UTR#20 and UTR#13 are well noted. However,
> just replacing <xhtml:br/> by <xhtml:br bdi='no'/> is not the correct
> solution. These reports point to <br/> because they assume that this is
> a well-known, simple reference. With the potential changes, this is no
> longer the case, and the UTRs have to find other ways to describe line
> separators in a way that is easily and immediately understandable.
> 3.2 Newlines in <pre>,...
> I clearly agree with this.
> 3.3 "embedded" block elements as bidi separators
> - This seems reasonable. I think the only reason it's not spelled out in
> HTML 4 is that there was an assumption that it didn't allow for
> 'free-floating' text besides block elements, either explicitly or by
> some SGML omittag trickery (but this assumption is clearly wrong for
> <div> within <div>).
> - "Since inline elements are not allowed to contain block elements...":
> At least when including CSS, this is not true. There are inline blocks.
> Such blocks should not be treated as separators, but as single
> characters. This means that this feature has to depend on whether the
> outside element is a block element or not.
> 3.4 Script dialog text
> I agree with the general direction this is going. However, it should be
> up to the HTML WG on how much of this behavior they what to prescribe,
> and at what level (MUST/SHOULD,...)
> 3.5 Title with dir=: agreed, but see 3.4
> 3.6 Direction of title and alt attributes: agreed, but see 3.4
> 3.7 <option>: agreed, but see 3.4
> 3.8 Set direction on <textarea>,...
> - This is valuable advice
> - In my understanding, what shortcuts to use for a particular
> functionality is not part of standardization, but part of browser
> differentiation. So we should leave it to the HTML WG whether they want
> to include this or not.
> 3.9 remember text directions: agreed, but see 3.4/3.8
> 3.10 bullets for lists: very strongly agree
> 3.11/3.12: scroll bars: agree, but see 3.4/3.8
> Appendix: "less better" -> "worse"
> Regards, Martin.

#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-# http://www.sw.it.aoyama.ac.jp   mailto:duerst@it.aoyama.ac.jp
Received on Monday, 15 March 2010 11:18:54 UTC

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