This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.

Bug 20085 - Description of BDI element needs to be updated after a change in the CSS unicode-bidi:isolate spec
Summary: Description of BDI element needs to be updated after a change in the CSS unic...
Status: RESOLVED WORKSFORME
Alias: None
Product: HTML WG
Classification: Unclassified
Component: HTML5 spec (show other bugs)
Version: unspecified
Hardware: PC Linux
: P2 normal
Target Milestone: ---
Assignee: Robin Berjon
QA Contact: HTML WG Bugzilla archive list
URL:
Whiteboard:
Keywords: CR
Depends on:
Blocks: 20126
  Show dependency treegraph
 
Reported: 2012-11-26 12:59 UTC by Aharon Lanin
Modified: 2013-04-23 23:49 UTC (History)
5 users (show)

See Also:


Attachments

Description Aharon Lanin 2012-11-26 12:59:01 UTC
The BDI element is currently described as follows:

> The bdi element represents a span of text that is to be isolated from its
> surroundings for the purposes of bidirectional text formatting. [BIDI]
> [...]
> For the purposes of applying the bidirectional algorithm to the contents of a
> bdi element, user agents must treat the element as a paragraph-level container.
>
> For the purposes of applying the bidirectional algorithm to the paragraph-level
> container that a bdi element finds itself within, the bdi element must be
> treated like a U+FFFC OBJECT REPLACEMENT CHARACTER (in the same manner that an
> image or other inline object is handled).

This description was based on the spec for unicode-bidi:isolate (http://www.w3.org/TR/2012/WD-css3-writing-modes-20120501/), through which BDI is implemented:

> For the purposes of the Unicode bidirectional algorithm, the contents of the
> element are considered to be inside a separate, independent paragraph with a
> base directionality given by the element's ‘direction’ property, and for the
> purpose of bidi resolution in its containing bidi paragraph (if any), the
> element itself is treated as if it were an Object Replacement Character
> (U+FFFC).

However, due to the subsequent addition of bidi isolates to Unicode (on track for Unicode 6.3), the inability of Unicode isolates to span across a paragraph break, and the desire to base CSS isolates on Unicode isolates, the CSS definition had to be modified (http://www.w3.org/TR/2012/WD-css3-writing-modes-20121115/):

> On an inline element, this bidi-isolates its contents. This is similar to a
> directional embedding (and increases the embedding level accordingly) except
> that each sequence of inline-level boxes uninterrupted by any block boundary
> or forced paragraph break is treated as an isolated sequence:
> * the content within the sequence is ordered as if inside an independent
> paragraph with the base directionality specified by the element's ‘direction’
> property.
> * for the purpose of bidi resolution in its containing bidi paragraph, the
> sequence is treated as if it were a single Object Replacement Character
> (U+FFFC).
> In effect, neither is the content inside the element bidi-affected by the
> content surrounding the element, nor is the content surrounding the element
> bidi-affected by the content or specified directionality of the element.
> However, forced paragraph breaks within the element still create a
> corresponding break in the containing paragraph.

The new CSS definition, and especially the note about forced paragraph breaks within the element (e.g. BR), should be reflected in the HTML spec of BDI.
Comment 1 Ian 'Hixie' Hickson 2012-11-28 18:26:41 UTC
(WHATWG spec bug 20126)
Comment 2 Robin Berjon 2013-04-23 23:49:55 UTC
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are
satisfied with this response, please change the state of this bug to CLOSED. If
you have additional information and would like the Editor to reconsider, please
reopen this bug. If you would like to escalate the issue to the full HTML
Working Group, please add the TrackerRequest keyword to this bug, and suggest
title and text for the Tracker Issue; or you may create a Tracker Issue
yourself, if you are able to do so. For more details, see this document:

   http://dev.w3.org/html5/decision-policy/decision-policy.html

Status: Accepted
Change Description: none
Rationale: This has already been fixed and merged.