[slowsmile]

Thanks to everyone -- particularly Diap and Hitch -- for clarifying what "cover image" refers to. I understand it now -- the term "cover image" also includes all cover refs in the opf directory. My mistake was to assume that the term "cover image" only referred to either the cover image file ref in the cover page or the cover image file itself in the Images directory.

DiapDealer said:

"Suffice to say that any add-on KDP validation process should probably be checking for meta entries (epub2), or manifest properties (epub3) to see if the mandatory cover image is indeed present. And it should be checking the guide section for a cover semantic to see if an xhtml cover page is present that Amazon advises against."

This plugin only checks epub2 files. If an epub3 file is checked with this plugin you will get an error. I also use the "name=cover" metadata ref(like Doitsu's Epubcheck) to check for the presence of a cover.

Currently the plugin only checks for the toc and start read point in the epub. If there are less than 2 refs in the guide, a warning will be shown. And if there are more than 2 refs in the guide(not including the cover ref) another warning is shown.

DiapDealer said:

"That's how I'd handle the cover page/image section of any KDP validation plugin I was creating for Sigil, anyway. I'd probably create an output plugin that did the checking and removed the xhtml cover page if present. That way content creators could maintain one main source epub, and could generate a KDP-compliant version on demand, so-to-speak."

I originally wanted the plugin to be a validation plugin and would prefer to keep it that way. This plugin just reports problems in much the same way as Epubcheck. I also think that the warnings and errors generated by the plugin should be enough for the plugin user to be able to fix all reported problems in much the same way as Epubcheck.

One last question. When the user removes the cover page from the epub, should he/she also remove the cover image file from the Images directory in Sigil as well?? If the answer is that it should also be removed then perhaps I should also add another plugin check to ensure that the original cover image file is also removed from the Images directory. My understanding is that the amazon product image will automatically be added to the epub Images directory on upload to KDP. Please let me know if I've got this wrong...