Re: EPUB Accessibility: Discovery of the Writing Direction (DRAFT 1.0)

>
>
> Some questions on the discoverability topic:
> 1. Can a publication be found for both D1 and D2 in your doc
> <https://1drv.ms/w/s!An5Z79wj5AZBgtUx_1os2PNRrYkDjA?e=v9qSpH>? I think
> yes for publications that can change the writing-mode but wanted to confirm.
>
>
Exactly.  See the note in 5.1.


> 2. If a non-switchable publication contains both writing-modes, how should
> it be found? As you know, a publication may have vertical chapters but book
> covers/chapter title pages/appendixes may be horizontal. Is it up to
> authors which writing-mode is "primary"?
>

I am aware that such publications exist.  In such cases,
I think that authors should indicate which direction is
primary.


> 3. I remember we had a discussion on page progression direction. CSS
> defines the page progression direction
> <https://drafts.csswg.org/css-writing-modes-3/#page-direction>, but it is
> only for an XHTML document (spine), and the page progression of a
> publication may be different, or an EPUB publication may contain mixed page
> progressions. Do you remember if we defined that, or did we leave it
> undefined, in the current EPUB spec?
>

The following paragraphs are extracted from EPUB Packages 3.2.
We might want to improve them on the basis of our experiences.
EPUB 3.3 is being developed by the EPUB 3 WG now.

The page-progression-direction attribute sets the global direction in which
the content flows. Allowed values are ltr (left-to-right), rtl (right-to-left)
and default. When the default value is specified, the Author is expressing
no preference and the Reading System can choose the rendering direction.
The default value *MUST* be assumed when the attribute is not specified. In
this case, the reading system *SHOULD* choose a default
page-progression-direction value based on the first language element.

Although the page-progression-direction attribute sets the global flow
direction, individual Content Documents and parts of Content Documents
*MAY* override
this setting (e.g., via the writing-mode CSS property). Reading Systems
*MAY* also provide mechanisms to override the default direction (e.g.,
buttons or settings that allow the application of alternate style sheets).

Reading Systems *MUST* ignore the page progression direction defined in
pre-paginated <https://www.w3.org/publishing/epub/epub-packages.html#layout>
XHTML
Content Documents. The page-progression-direction attribute defines the
flow direction from one fixed-layout page to the next.


> A minor point: if the word "discovery" in your doc has a specific meaning
> in an existing spec, it is helpful if you can link the word to the
> definition.
>

Noted.   Will think about this.

Regards,
Makoto