unicode-bidi

Summary

The unicode-bidi CSS property together with the direction property relates to the handling of bidirectional text in a document. For example, if a block of text contains both left-to-right and right-to-left text then the user-agent uses a complex Unicode algorithm to decide how to display the text. This property overrides this algorithm and allows the developer to control the text embedding.

The unicode-bidi and direction properties are the two only properties that are not affected by the all shorthand.

Note: This property is intended for DTD designers. Web designers and similar authors should not override it.

  • Initial value normal
  • Applies to all elements, though some values have no effect on non-inline elements
  • Inherited no
  • Media visual
  • Computed value as specified
  • Animatable no
  • Canonical order the unique non-ambiguous order defined by the formal grammar

Syntax

Formal syntax: normal | embed | isolate | bidi-override | isolate-override | plaintext
unicode-bidi: normal
unicode-bidi: embed
unicode-bidi: isolate
unicode-bidi: bidi-override
unicode-bidi: isolate-override
unicode-bidi: plaintext

unicode-bidi: inherit

Values

normal
The element does not offer a additional level of embedding with respect to the bidirectional algorithm. For inline elements implicit reordering works across element boundaries.
embed
If the element is inline, this value opens an additional level of embedding with respect to the bidirectional algorithm. The direction of this embedding level is given by the direction property.
bidi-override
For inline elements this creates an override. For block container elements this creates an override for inline-level descendants not within another block container element. This means that inside the element, reordering is strictly in sequence according to the direction property; the implicit part of the bidirectional algorithm is ignored.
isolate
This keyword indicates that the element's container directionality should be calculated without considering the content of this element. The element is therefore isolated from its siblings. When applying its bidirectional-resolution algorithm, its container element treats it as one or several U+FFFC Object Replacement Character, i.e. like an image.
isolate-override
This keyword applies the isolation behavior of the isolate keyword to the surrounding content and the override behavior of the bidi-override keyword to the inner content.
plaintext
This keyword makes the elements directionality calculated without considering its parent bidirectional state or the value of the direction property. The directionality is calculated using the P2 and P3 rules of the Unicode Bidirectional Algorithm.
This value allows to display data which has already formatted using a tool following the Unicode Bidirectional Algorithm.

Examples

.bible-quote {
  direction: rtl;   
  unicode-bidi: embed;
} 

Specification

Specification Status Comment
CSS Writing Modes Module Level 3 Working Draft Added plaintext, isolate, and isolate-override keywords
CSS Level 2 (Revision 1) Recommendation  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 2.0 1.0 (1.7 or earlier) 5.5 9.2 1.3
isolate 16 -webkit [1] 10 (10) -moz [2] Not supported Not supported Not supported
plaintext Not supported 10 (10) -moz Not supported Not supported Not supported
isolate-override Not supported 17 (17) -moz Not supported Not supported Not supported
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 1.0 1.0 (1.0) 6 8 3.1
isolate ? 10.0 (10) -moz Not supported Not supported Not supported
plaintext Not supported 10.0 (10) -moz [3] Not supported Not supported Not supported
isolate-override Not supported 17.0 (17) -moz Not supported Not supported Not supported

[1] Since Chrome 19, the syntax from a previous version of the spec, where the isolate keyword could be used together with bidi-override, is allowed.

[2] From Firefox 10 to Firefox 16 included, the old version of the spec, where the isolate keyword could be used together with bidi-override, was implemented. From Firefox 17, this is no longer possible: only one value is allowed and the previous isolate bidi-override can be described using the new isolate-override keyword.

[3] Up to Firefox 15, plaintext didn't do anything to an inline element. The specification changed and the implementation was fixed in Firefox 15.

See also

Document Tags and Contributors

Contributors to this page: Sheppy, ethertank, Krinkle, kscarfone, teoli, McGurk
Last updated by: kscarfone,
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