I am browsing available (Calibre related) epub files. And actually cannot find any guide item "titlepage"... But Calibre surely have to be related into it somehow: simply because guide item "titlepage" do not generate "Go to..." menu item (unlike any other guide item type).
On the other hand, what I
can see
everywhere is guide item "cover", but pointing on html (not image)...:
Code:
<guide>
<reference type="cover" href="titlepage.xhtml" title="Cover"/>
</guide>
Such markup is generated e.g. during conversion from docx, or using (right click) menu item "Mark filename.xhtml as cover page" in editor...
I would sware I before met information that guide item "cover" can be used to identify cover image file (besides of second method via manifest/meta[@name="cover"] etc.)... But now, I can't find such info again. Just examples of cover item pointing to html file...:
https://epubsecrets.com/where-do-you...e-opf-file.php
https://wiki.mobileread.com/wiki/Ebook_Covers