Glyph orientation and joining behaviour in vertical text

[r12a]

There are certainly attested instances of lines of Arabic script text that run in a vertical direction on book spines and the like. In such cases, the text is all joined up and glyphs are rotated so that the text flows as normal, and just the line orientation is changed.

What is not clear is whether there is a requirement for supporting Arabic script text, for Arabic & Persian, in vertical lines in a way which is more like Chinese or Japanese, ie. with upright letter forms.

However, there are also attested cases of Arabic text arranged vertically with the letters upright, for example in signboards for cinemas or theatres. It is not clear, at this point whether this should be regarded as a standard approach for Arabic text, and one for which support is needed in CSS, SVG, and other technologies, or whether this is just an unusual layout that mimics Western typographic approaches. Here is an example outside a movie theatre:

The following should be noted:

• Letters flow from top to bottom (as with Latin script)
• Isolated forms of letters are used.
• Diacritic marks, if any, should be applied to letters and not appear on separate lines.

This issue asks the question: Is there a need to support this latter layout for Web pages and eBooks, using W3C technologies?

[gounaman]

I would say this also applies to vulgar fractions. In this case, the vinculum ought to have the option of appearing slanted.