Hello, Kovid! I'm honored that Calibre's creator is willing to try and help me solve this EPUB conundrum.
From what you're saying, my instinct is right: it's not an EPUB issue from my end. iTunes must set up all these obstacles to test just how badly you want your eBook made available there!
Anyway, now that we've gotten into it, here are the first three error messages I've gotten (there are more, but you get the idea):
ERROR ITMS-9000: "I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub: /Users/brighthorse/Music/iTunes Producer/Playlists/9780692979266.itmsp/I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub/iSam_ebook_fixed_split_023.html(14): [RSC-005] Error while parsing file 'attribute "_title" not allowed here; expected attribute "accesskey", "charset", "class", "coords", "dir", "hreflang", "id", "lang", "rel", "rev", "shape", "style", "tabindex", "target", "title", "type" or "xml:lang"'..
This error occurs 465 times. (For more information refer to http://support.apple.com/kb/HT6213)" at Book/BookAssets
ERROR ITMS-9000: "I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub: /Users/brighthorse/Music/iTunes Producer/Playlists/9780692979266.itmsp/I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub/iSam_ebook_fixed_split_023.html(14): [RSC-005] Error while parsing file 'attribute "to" not allowed here; expected attribute "accesskey", "charset", "class", "coords", "dir", "hreflang", "id", "lang", "rel", "rev", "shape", "style", "tabindex", "target", "title", "type" or "xml:lang"'..
This error occurs 465 times. (For more information refer to http://support.apple.com/kb/HT6213)" at Book/BookAssets
ERROR ITMS-9000: "I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub: /Users/brighthorse/Music/iTunes Producer/Playlists/9780692979266.itmsp/I_Samantha_Take_This_Mortal_Darrin_-_Adam-Michael_James.epub/iSam_ebook_fixed_split_023.html(14): [RSC-005] Error while parsing file 'attribute "chapter" not allowed here; expected attribute "accesskey", "charset", "class", "coords", "dir", "hreflang", "id", "lang", "rel", "rev", "shape", "style", "tabindex", "target", "title", "type" or "xml:lang"'..
This error occurs 465 times. (For more information refer to http://support.apple.com/kb/HT6213)" at Book/BookAssets
It turns out "...split_023.html" is the section that contains all my endnotes. Of which there are...465. So that narrows that down.
Here is a small sampling of my HTML that includes links meant to take my readers back to the the passage from where they clicked on the endnote:
<p id="e1016">16. <em>The Bewitched Continuum</em>, pg. 223<a href="#ref1016" "title=return to Chapter 10">↺</a></p><br>
<p id="e1017">17. “Mrs. Stephens, Where Are You?” (#160)<a href="#ref1017" "title=return to Chapter 10">↺</a></p><br>
<p id="e1018">18. “Samantha on Thin Ice” (#246)<a href="#ref1018" "title=return to Chapter 10">↺</a></p><br>
This all works fine on the eReaders I've tested it on...including iBooks!
So if this fills in any blanks...!
I thank you, Kovid, for filling in a few more me. iTunes Producer shall not win this battle! I shall be vindicated! LOL