Text Directionality Workgroup

Text Directionality Workgroup
This page will summarize the evolving work of the Text Directionality Workgroup, tasked by the TEI Council with developing a new section for the Guidelines on recommendations for encoding a variety of textual features related to text directionality and orientation. The related SourceForge ticket is http://purl.org/tei/fr/3475007.

Workgroup Members

 * Martin Holmes (TEI Council)
 * Deborah W. Anderson (Unicode Consortium)
 * Robert Whalen (Northern Michigan University)
 * Marcus Bingenheimer (Temple University)
 * Stella Dee (King's College, London)

Order of Tasks

 * Enumerate textual features to be covered
 * Collate existing standards and recommendations and relate them to features
 * Identify any gaps which might require new TEI elements or attributes
 * Outline the new section
 * Write the first draft for consideration by Council
 * Identify other places in the Guidelines where information or links need to be included

Mailing List
The group has a mailing list provided through Brown University at http://listserv.brown.edu/archives/cgi-bin/wa?A0=TEI-DIR-WG.

Notes from initial discussions

 * We agree (so far) that we would like to distinguish between two distinct types of phenomena: "true" text directionality (such as that found in language such as Japanese written vertically ttb with lines sequence rtl -- and "rotational" features, in which text written in any direction is rotated or written along a path. Our proposal will have to cover both of these phenomena, and provide for cases in which they interact, but they will probably be handled by different mechanisms.


 * We agree that the ITS specification is rather a red herring. Its primary concern is translation rather than text representation, and its provisions for directionality are sparse.


 * We agree that the CSS Writing Modes draft provides the best descriptive introduction to directional phenomena.

Examples, constructed and from primary sources
This section collects together some examples which our discussion can reference. We aim to collect useful examples of some straightforward cases, but also of some edge cases which our proposal must be able to handle. Some of these may be used as examples in a final draft of the new section of the Guidelines. These are listed in no particular order.

Text directionality

 * Wikipedia has some good examples of Boustrophedon (alternate lines running in different directions, with glyphs also flipped horizontally for rtl lines).
 * Ancient Berber is an example of a script written bottom-to-top, with lines right-to-left.
 * This Berber inscription also incorporates rotation, so we could demonstrate the combination.

Rotation

 * Rotation along X axis: [[File:Rotation_on_x_axis.png‎]] "tei-c.org" 180 deg: "ʇǝı-ɔ˙oɹƃ"
 * Rotation along Y axis: [[File:Rotation_on_y_axis.png‎‎]]
 * Rotation along Z axis: [[File:Rotation_on_z_axis.png‎]]


 * Easter Wings is a good real-world example of rotation along the z axis.
 * Arabic text written along a circular path (a roundel).

Useful documents

 * UTR 50, Unicode Properties for Horizontal and Vertical Text Layout
 * Forum for UTR 50
 * UAX 9, Unicode Bidirectional Algorithm
 * Unicode BIDI forum
 * UTR 20, Unicode in XML
 * what you need to know about the bidi algorithm and inline markup
 * Unicode controls vs markup for bidi support
 * CSS Writing Modes
 * CSS vs Markup in XHTML