Enhanced Global Language Support(EGLS) in EPUB
Subgroup Recommendation October 17, 2010
Slightly revised for incorporating the SF F2f decisions.
Table of Contents
This document provides recommendations from the EGLS sub-group to the EPUB 3.0 WG. These recommendations are intended to provide solutions to the requirements shown in the EGLS requirements wiki page
These recommendations are based on the consensus reached in the EGLS face-to-face meeting in Taipei 2010-10-05/06. Rationales for each recommendations can be found in either the solution wiki or the minutes of the meeting. The mintues of the meeting will be provided in the very near future.
Details of the interaction between these two mechanisms will be provided by Takeshi Kanai and Koji Isshi.
rbelement if it is introduced to HTML5.
rpelement in OPS. Require that implementations not supporting ruby layout add such parentheses (as required by HTML5).
To aid Reading Systems in implementing consistent searching and sorting behavior it is required that Unicode Normalization Form C (NFC) be used (See http://www.w3.org/TR/charmod-norm/).in the Relationship to Unicode sections ( Section 1.3.6. of OPS and Section 1.3.4 of OPF) to
To aid Reading Systems in implementing consistent searching and sorting behavior, content providers may apply Unicode Normalization Form C (NFC) (See http://www.w3.org/TR/charmod-norm/).with a warning on the issue regarding CJKV compactibility characters. + +
[Changes agreed in the SF F2F: Remove the normalization section entirely from the spec.]
[Changes agreed in the SF F2F: Priviate use characters must be accompanied by embedded fonts.]
Note: This makes the interpretation of metadata where multiple elements are allowed ambiguous. For example, it is not clear whether there are two contributors or one with two name varaints. The resolution of this issue is deferred to the metadata subgroup.
[Changes agreed in the SF F2F: Clearly state that the xml:lang attribute of a meta element in OPF 3.0 specifies a language variant of the metadata in scope. As an example, mention the use of ja-kana-jp, zh-bopo, zh-Latn-pinyin as value of xml:lang for denoting the pronunciation of the metadata. ]
[Changes agreed in the SF F2F: Use the package element dcterms:language in OPF 3.0 as the default language of all the enclosed OPS documents. ]
Note: If css3-fonts is not ready, this is effectively replacing an existing normative requirement in EPUB2, not adding anything new. See also Section 3.5.
This module defines support for various international writing directions, such as left-to-right (e.g., Latin scripts), right-to-left (e.g., Hebrew or Arabic), bidirectional (e.g., mixing Latin with Arabic) and vertical (e.g., Asian scripts). It extends properies that are long-existing in CSS2 such as unicode-bidi. It is essential to enhanced global language support.
Although this specification is not yet published by W3C as a working draft, the editor (fantasai) is optimistic about the future of this spec since there's an exsisting implementation by Antenna House and an ongoing implementation by the Webkit team. Two interoperable implementations greatly help this spec towards a W3C recommendation, since one of the criteria for a W3C recommendation is two interoperable implementations.
The relevant solutions to the requirements are: Two Styles of Vertical Writing, Writing Mode of Captions and Table Entries, Providing Reasonable Fallbacks to Horizontal Writing, One by One, Tate-chu-yoko.
This CSS3 module defines properties for text manipulation and specifies their processing model. It covers line breaking, justification and alignment, white space handling, text decoration and text transformation. Line breaking and justification are highly area-dependendent (CJK area, Southeast Asia, Arabic, Mongolian are covered) and hence this specification certainly adresses the need of EGLS.
This specification is now very active. It was published as a W3C published draft very recently. It is expected to reach the state of Candidate Recommendation in early 2011.
This module defines a pattern for tagging alternate style sheets using a microformat, where certain values of the class attribute on a (X)HTML link element are standardized. It can be used to define standardized classes that can be hooked into the browser UI. Sample use cases include horizontal-vertical layout switches in Japanese Ebook readers; automatically selecting high-contrast styles; and other accessibility concerns.
This is a simple extenstion to the existing alternate style mechanism in (X)HTML, and its inplementation cost should be pretty low. This spec does not currently belong to a standard body. Makoto Murata might bring this specification to the EPUB Working Group.
The relevant solutions to the requirements are: Principal Writing Mode, Providing Reasonable Fallbacks to Horizontal Writing, Providing Optimal Layouts for more than one Principal Writing Mode, Announcing non-optimality.
This document has been developed by Enhanced Global Language Support sugroup of the International Digital Publishing Forum (IDPF)'s EPUB working group. Group members and face-to-face meeting attendees are listed as follows: