[BetterRed]

@rellwood - Firstly calibre has two main export mechanisms - Send to Device and Save to Disk.

As I understand them Plugboards are a mechanism for mapping the metadata columns (fields) in the calibre database to the metadata fields within an ebook format. So lets say I have a custom column called Status. I know for certain that none of the formats or devices out there will know about my Status column. So via a plugboard I could plug the value of my Status column into the Title in the ebook metadata as a prefix.

I can't address the Automerge issue, I don't use it.

I gave up on trying to de-dup my initial library in-situ. I did this: I processed books in smallish batches (about 50 I think). I added 50 books to a "Workbench" library and focuss[sic]ed on getting the author, title and ISBN correct and consistent. I deduped that set of books with the Find Duplicates plugin, then moved what was left to a "Good" library. For the second and subsequent batches after deduping the batch, I used the Find Duplicates->Library Duplicates feature (checks for duplicates across two libraries) to weed out inter library duplicates. I dumped duplicates into a "Bad" library... rinse and repeat....

My plan was to use the "Bad" library as a source of 'missing' metadata, I soon discovered that it was far easier to download metadata from Amazon, Goodreads etc and/or roll my own - especially with tags.

Calibre does use hardlinks for reasons of performance when it makes sense to do so - in move and rename operations. But they are transient, ie when calibre has done what it needs to do there is only one link. So users are not aware of them.

The word 'link' is also used within the calibre forum in the context of linking calibre authors and books to supplementary data about the author or book via a URI.

For authors there is a specific feature, the Author Link property which is accessible via Manage Authors. For books you can insert <a href= style links into long text columns (including Comments), you could put your URI into the Identifiers column, I found this awkward so I prefer the long text column method.

And Author Link or a link in a the long text column can contain any valid URI - I know these work, Web urls (http(s)://...), FTP urls (ftp(s)://...), FILE uri's (file:///...), Evernote uris (evernote:///...) and OneNote uris (onenote:///...)

BR