Pop-up footnotes in sideloaded kepubs gone AWOL in fw 4.0.7523

I'm creating this post as a repository for information following several reports of footnote links in sideloaded kepubs no longer appearing as pop-ups on the AuraOne with firmware 4.0.7523.

For all de-DRM'd epub2 format books tested so far (about 30 of them), I've managed to get kepub footnotes to pop-up by doing the following:

1. Physically remove any non-working kepub from the Kobo before proceeding. I think this is safest because step 2 will reorganise the internal structure of the epub.
   
   
2. Open the source standard epub in the calibre Editor and use the Tools - Arrange into folders option to reorganise the epub internal file structure as per the attached image.
   
   
3. Check the HTML code controlling the footnotes. Each footnote is made up of a "matched pair", the code in the chapter text and the code in the footnotes/endnotes file.
   
   The chapter file HTML code should look similar to:
   
   Code:

   ---

   <p class="indent">Text in chapter with a footnote link.<a id="retfn01" href="footnotes.xhtml#fn01">[1]</a></p>

   ---

   and the footnote/endnote file HTML code similar to
   
   Code:

   ---

   <p class="footnote"><a id="fn01" href="chapter.xhtml#retfn01">[1]</a>Explanatory footnote text</p>

   ---

   I have no reason to believe the class names or filenames are important. The footnote id names may not be important either.
   
   
4. If either or both of the pieces of HTML code are styled using a <sup> or <span class="..."> tag to give the '[1]' text a superscript appearance, make sure the <a> anchor tag is the innermost tag and the <sup>/<span> the outer tag, not vice versa. E.g.
   
   Code:

   ---

   <sup><a id="retfn01" href="footnotes.xhtml#fn01">[1]</a></sup>

   ---

5. Use KoboTouchExtended calibre driver to send-to-device the epub-as-kepub in the normal way.

Notes:

• Anyone who is not comfortable with steps 3 and 4 could try excluding these steps. Footnotes not coded this way may never have popped up in previous firmwares either. Perhaps your books are already correctly coded if they had working pop-ups on a non-AuraOne Kobo using fw3.19.
• In case anyone is wondering, I have no idea why step 2 has become necessary. It maybe that many different internal file layouts will also work, but I do know my previous preferred layout no longer works.
• I have not done enough testing on epub3-sent-as-kepub books which use the newer epub3 method for coding footnotes to reach any conclusions about the best way to make epub3 kepub footnotes pop-up. Personally, I don't have any epub3s with footnotes and I don't want to spend any more time troubleshooting on a firmware which is so close to being superceded. Of course, any contributions from others are most welcome.

Obviously I have no way of knowing whether this method will still work with the new firmware promised for next week :)

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