Ruby character

Uses

Ruby may be used for different reasons:

• because the character is rare and the pronunciation unknown to many—personal name characters often fall into this category;
• because the character has more than one pronunciation, and the context is insufficient to determine which to use;
• because the intended readers of the text are still learning the language and are not expected to always know the pronunciation or meaning of a term;
• because the author is using a nonstandard pronunciation for a character or a term

Also, ruby may be used to show the meaning, rather than pronunciation, of a possibly unfamiliar (usually foreign) or slang word. This is generally used with spoken dialogue and applies only to Japanese publications. The most common form of ruby is called furigana or yomigana and is found in Japanese instructional books, newspapers, comics and books for children.

In Japanese, certain characters, such as the sokuon (促音) (little tsu, っ) that indicates a pause before the consonant it precedes, are normally written at about half the size of normal characters. When written as ruby, such characters are usually the same size as other ruby characters. Advancements in technology now allow certain characters to render accurately.

In Chinese, the practice of providing phonetic cues via ruby is rare, but does occur systematically in grade-school level text books or dictionaries. The Chinese have no special name for this practice, as it is not as widespread as in Japan. In Taiwan, it is known as "zhuyin", from the name of the phonetic system employed for this purpose there. It is virtually always used vertically, because publications are normally in a vertical format, and zhuyin is not as easy to read when presented horizontally. Where zhuyin is not used, other Chinese phonetic systems like pinyin are employed.

In academic settings, Vietnamese text written in chữ Hán or chữ Nôm may be glossed with chữ quốc ngữ ruby for modern readers.

Sometimes interlinear glosses are visually similar to ruby, appearing above or below the main text in smaller type. However, this is a distinct practice used for helping students of a foreign language by giving glosses for the words in a text, as opposed to the pronunciation of lesser-known characters.

Ruby annotation can also be used in handwriting.

History

In British typography, ruby was originally the name for type with a height of 5.5 points, which printers used for interlinear annotations in printed documents. In Japanese, rather than referring to a font size, the word became the name for typeset furigana. When transliterated back into English, some texts rendered the word as rubi (a typical romanisation of the Japanese word ルビ, instead of ルビー (rubī), the expected transliteration of ruby). However, the spelling "ruby" has become more common since the W3C published a recommendation for ruby markup. In the US, the font size had been called "agate", a term in use since 1831 according to the Oxford English Dictionary.

HTML markup

In 2001, the W3C published the Ruby Annotation specification for supplementing XHTML with ruby markup. Ruby markup is incorporated into the XHTML 1.1 specification and in HTML5.

For browsers that do not support Ruby natively, Ruby support is most easily added by using CSS rules that are available on the web.

Ruby markup is structured such that a fallback rendering, consisting of the ruby characters in parentheses immediately after the main text, appears if the browser does not support ruby.

The W3C is also working on a specific ruby module for CSS level 2, which additionally allows the grouping of ruby and automatic omission of furigana matching their annotated part.

Markup examples

Below are a few examples of ruby markup. The markup is shown first, and the rendered markup is shown next, followed by the unmarked version. Web browsers either render it with the correct size and positioning as shown in the table-based examples above, or use the fallback rendering with the ruby characters in parentheses:

Chinese ruby text would normally be displayed in vertical columns to the right of each character. This approach is not typically supported in browsers at present.

This is an example of vertical columns: 瓶 (ㄆㄧㄥˊ)子 (˙ㄗ)

Complex ruby markup

Complex ruby markup makes it possible to associate more than one ruby text with a base text, or parts of ruby text with parts of base text.

Unicode

Unicode and its companion standard, the Universal Character Set, support ruby via these interlinear annotation characters:

• Code point FFF9 (hex)—Interlinear annotation anchor—marks start of annotated text
• Code point FFFA (hex)—Interlinear annotation separator—marks start of annotating character(s)
• Code point FFFB (hex)—Interlinear annotation terminator—marks end of annotated text

Few applications implement these characters. Unicode Technical Report #20 clarifies that these characters are not intended to be exposed to users of markup languages and software applications, and are instead for internal use either in systems or the applications themselves. It suggests that ruby markup be used instead, where appropriate.

The interlinear annotation characters are part of the "Specials" Unicode block:

ANSI

ISO/IEC 6429 (also known as ECMA-48) which defines the ANSI escape codes also provided a mechanism for ruby text for use by text terminals, although few terminals and terminal emulators implement it. The PARALLEL TEXTS (PTX) escape code accepted six parameter values giving the following escape sequences for marking ruby text:

• CSI 0 \ (or simply CSI \ since 0 is used as the default value for this control) – end of parallel texts
• CSI 1 \ – beginning of a string of principal parallel text
• CSI 2 \ – beginning of a string of supplementary parallel text
• CSI 3 \ – beginning of a string of supplementary Japanese phonetic annotation
• CSI 4 \ – beginning of a string of supplementary Chinese phonetic annotation
• CSI 5 \ – end of a string of supplementary phonetic annotations