Rb (Ruby Base)

Support Key: [2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
What is it?
Tag Example
Parent/Content Model
Tips & Tricks
Browser Peculiarities
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Standards Details:
Support beginning in XHTML 1.1 DTD.
XHTML Modules:
CSS 'display' Type:
CSS Mapping:
Default Rendering:
Official Docs:
XHTML 1.1: Ruby Module

What is it?
A Ruby is part of an annotation pair - a piece of text ("Ruby Text") that is associated with another piece of text known as a "Ruby Base". A common need for such a structure arises in some asian writing systems where a ruby association is used to present helper readings for uncommonly used writing characters.

With a character set as complex as Chinese or Japanese, some characters are used rarely and are thus not as easily recognizable by younger children or possibly many adults. In Japanese writing, for example, the phonetic Hiragana alphabet is used to pair phonetic 'helper' readings (called Furigana or Yomigana in Japanese) with the Chinese character counterpart.

A Ruby text will usually be rendered next to the Base text such that the association between each Base text and Ruby text is clear (often directly above the Base text.) Ruby text is usually also rendered in a smaller font than the Base text to help visually clarify which part is which in the association relationship.

Ruby markup has two main usage modes in XHTML - Simple Rubies, where a single annotation or helper text is associated with a single piece of Base text, and Complex Rubies, where as many as two Ruby text annotations can be bound to a single piece of Base text. Complex Rubies also allow Base text and Ruby text to be broken down further, so that even more detailed associations can be made between them.

Simple Rubies
Simple Rubies will often be the only type of annotation mechanism that most authors need. In this type of ruby markup, two main elements exist nested in the RUBY element - the Base text (the RB element), followed by the Ruby text (the RT element.)

For browsers that do not understand the RUBY markup, they will display the content of the RT element directly following the contents of the RB content. Since this sort of fallback may not be enough to distinguish the association relationship between the two content pieces, one final, optional fallback element is provided to make the association clear in non-supporting browser scenarios: the RP element. An RP element containing a single character (usually an open or close parenthesis, depending on the context - RP DOES stand for Ruby Parenthesis...) should be put on either side of the RT element. Ruby-supporting browsers should ignore the RP element completely and not render it in any way; in non-supporting browsers however, the contents of the RP element will surround the RT content to tie the content with the previous RB content.

Complex Rubies
Complex rubies can have multiple Base elements, and multiple Ruby Text components. In a Complex Ruby, all of the Base elements (RB) are enclosed in an RBC element (RBC: Ruby Base Container.) For the Ruby Text elements (RT), these are enclosed in an RTC element (RTC: Ruby Text Container.) A Complex Ruby can have one or two RTC elements which allows for two text associations to be given for any given Base text. Default rendering might render the first RTC group ABOVE the Base text, with the second RTC group possibly rendered BELOW the Base text... but, this rendering is definitely not guaranteed - allowances for alternate writing directions (eg: vertical rather than horizontal) and other criteria can complicate rendering, and CSS properties have already been proposed specifically for Ruby markup in future CSS versions to control these details.

The content of the Ruby Base Container (RBC) is, of course, RB elements. Similarly, the content of any Ruby Text Containers (RTC) are RT elements. With Complex Rubies, RT elements have an additional attribute RBSPAN which acts like COLSPAN does for TD and TH elements in tables - it allows a piece of Ruby Text content to be associated with multiple RB base elements. If the RBSPAN attribute is specified, the number of RT elements used is decreased by one for every RB element that it encompasses.

Common Attributes
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
Simple Ruby example:
   <rp>(</rp> <rt>HyperText Markup Language</rt> <rp>)</rp>
Complex Ruby example:
   <rt rbspan="3">Uniform Resource Locator</rt>
Parent Model
<ruby> | <rbc>
Content Model
%In-line Content%
Exceptions: <ruby>
Tips & Tricks Browser Peculiarities
Boring Copyright Stuff...