This will be a killer feature. I use DEVONthink as a knowledge base, which of course, includes a lot of books. EPUB and PDF are the main formats for ebooks; DEVONthink’s support for PDF is excellent (actually, that’s the reason I bought DEVONthink). However, DEVONthink’s support for EPUB isn’t quite as good. I don’t expect DEVONthink to be able to annotate and comment on EPUBs like PDFs, but having the ability to “copy selection link” would be a great start.
Part of the issue is that a link to an ePub always opens the ePub in Best Alternative view, so that deeplink search operators like ?line= (generated by Copy with Source Link) or ?search= (manually appended) will only take you back to the text you want if it occurs on the ePub’s default landing page.
If you have an ePub open in Text Alternative view with an annotation file open in the inspector, you can use Copy with Source Link on a selection and paste it into the annotation file, and then the link in the annotation will take you to the correct paragraph so long as you already have the ePub open in Text Alternative in the Preview window. Similarly, in the same arrangement if you manually append a ?search= operator to the document link in the annotation, clicking on the link will take you to the text in your search string (which is how DT selection links work in PDFs) – though you do have to URL-encode the search string, something that’s done automatically by the Copy Selection Link command in PDFs. Nevertheless, if there were a setting to make ePubs open by default in Text Alternative view, it would be possible at least to create the effect of a Selection Link in an ePub, albeit with a bit more manual fiddling.
Deep linking in PDFs has been one of the most compelling recent feature additions in DT, and one of the elegant things about it is that it’s implemented by the existing search operator functionality, which is largely agnostic of document type. The reason it’s easier to implement in PDFs is that text strings are readily marked by page number and character offset, but an ePub in Text Alternative view is essentially a single searchable page, so those of us who need deep linking in ePubs would be able to fudge it if we could open in Text Alternative by default.
I use Calibre to read and annotate EPUBS for it’s ability to link to a specific annotation and index the books in DT. Then when I am done, I export the annotations from Calibre as MD…