RE: EPUBCheck 4.2.1 error message issue raised from Japan

Hello,
 
To clarify about navigation for me, here is a short description:
 
In an HTML or XHTML document, I will navigate by headings. I press “h” and my screen reader takes me to the next heading in the document. I can refine this and ask for the next h1, or h2, etc.
 
This means that the navigation document does not necessarily need to have all the headings in a title. Some publishers may choose to have only h1 and h2 in the navdoc, which is fine. Once I am in the chapter I use the local navigation to navigate to lower level headings.
 
We see this same construction in printed books, where the heading structure is very detailed, but the publisher chooses to only put the first few levels in the print TOC.
 
Best
George
 
From: MURATA Makoto <eb2m-mrt@asahi-net.or.jp> 
Sent: Sunday, June 23, 2019 7:32 AM
To: Daihei Shiohama <shiohama@mediado.jp>
Cc: AUDRAIN LUC <LAUDRAIN@hachette-livre.fr>; McCloy-Kelley, Liisa <lmccloy-kelley@penguinrandomhouse.com>; Ivan Herman <ivan@w3.org>; W3C Publishing Business Group <public-publishingbg@w3.org>
Subject: Re: EPUBCheck 4.2.1 error message issue raised from Japan
 
Folks,
 
Although I agree on the proposed changes to EPUBCheck, I 
do not think that we should stop there.
 
Having seen examples summarized by Takami-san, I now think 
that future EPUB publications will continue to have this 
idiosyncrasy: the occurrence order in the navigation document 
will be different from that in the spine.
 
How can we make such EPUB publications accessible?  
Some people (e.g., blind people) heavily rely on structural 
navigation, which is driven by navigation documents.  Won't 
they be mislead?  If so, is it possible to improve EPUB for 
overcoming this problem?


 
-- 
Regards,
Makoto