The <bdo> Tag
As we mentioned earlier, the authors of the HTML 4
standard made a concerted effort to include standard ways that web
agents (browsers) are supposed to treat and display the many different
human languages and dialects. Accordingly, the HTML 4 standard and its
progeny, XHTML, contain the universal dir
and lang
attributes that let you explicitly advise
the browser that the whole document or specific tagged segments within
it are in a particular language. These language-related attributes,
then, may affect some display characteristics; for example, the dir
attribute tells the browser to write the
words across the display from either left to right (dir=ltr
), as for most Western languages, or
right to left (dir=rtl
), as for many
Asian languages.[The dir
attribute, 3.6.1.1] [The
lang attribute, 3.6.1.2]
The various Unicode and ISO standards for language encoding and
display may conflict with your best intentions. In particular, the
contents of some other documents, such as a Multipurpose Internet Mail
Extension (MIME)-encoded file, may already be properly formatted, and
your document may misadvise the browser to undo that encoding. Hence,
the HTML 4 and XHTML standards have the <bdo>
tag. With it, you override any
current and inherited dir
specifications. And with the tag’s required dir
attribute, you definitively specify the
direction in which the tag’s contents should be displayed.
For example, Figure 3-5 shows how Internet Explorer handles the following HTML fragment ...
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