Specifies the base direction of directionally neutral text and the directionality of tables.
This attribute specifies the base direction of directionally neutral text (i.e., text that doesn't have inherent directionality as defined in [UNICODE]) in an element's content and attribute values. It also specifies the directionality of tables. Possible values:
- LTR: Left-to-right text or table.
- RTL: Right-to-left text or table.
In addition to specifying the language of a document with the lang attribute, authors may need to specify the base directionality (left-to-right or right-to-left) of portions of a document's text, of table structure, etc. This is done with the dir attribute.
The [UNICODE] specification assigns directionality to characters and defines a (complex) algorithm for determining the proper directionality of text. If a document does not contain a displayable right-to-left character, a conforming user agent is not required to apply the [UNICODE] bidirectional algorithm. If a document contains right-to-left characters, and if the user agent displays these characters, the user agent must use the bidirectional algorithm.
Although Unicode specifies special characters that deal with text direction, HTML offers higher-level markup constructs that do the same thing: the dir attribute (do not confuse with the DIR element) and the BDO element. Thus, to express a Hebrew quotation, it is more intuitive to write
<Q lang="he" dir="rtl"