title_body: Universal Identification metadata for e-books I would like to add to my ebooks some reference metadata so as to be
  able to easily find information on the web, without using a search
  that is often tedious, possibly difficult since each search engines
  has its own (weird?) way of using the search information.
  
  I noticed that many site have each their own identification system,
  not to mention the ISBN standard numbers, which many do not use.
  It also seems that none of these system covers all books.
  
  Ideally, I would like to use only one identification for each book,
  though possibly not the same for all. My idea was to identify a book
  with a pair [ &lt;ID system> , &lt;book ID> ], so that I would not be
  constrained to any specific identification system, which is necessary
  to deal with the limited coverage of each identification system.
  
  I can give as example the book "Dead and Buryd" by Chele Cooke (I have
  not read it). I could identify it as:
  
     [ ISBN , 1230000171483 ]
     [ SMSH , 358812 ]           for Smashwords
     [ ASIN , B00FLVRWYU ]       for Amazon
     [ KOBO , "dead-and-buryd" ] for Kobo
     [ GDRD , 21895867 ]         for Goodreads
  
  
  In each case, this is all the information I need to retrieve the book page
  on the corresponding site, and access whatever information is
  available there. One can easily build a usable URL from each pair (except, may-be, for ISBN).
  
  My question is whether this idea has been previously developed for
  whatever purpose (probably with other names than the ones I chose),
  and whether one can find on the web correspondance tables,
  so that, given one identification pair, I can find an identification
  pair for the same book in another ientification system.
  
  For example, given [ SMSH , 358812 ], I could ask for the GDRD
  identification and get [ GDRD , 21895867 ].
  
  Is there anything in Calibre to help building such tables?
  
  Note: I am aware that the use of ISBN may be a bit more complex, but I
  did not want to add that complexity to the question. I also know that the definition of "book" may or may not include a variety of things, such as edition. But I want to start simply.
  
  Note: I corrected an unfortunate metalinguistic error, which caused part of the text to be taken as a HTML tag. Still, though I would expect that many users do not have information to contribute, I am surprised that no one showed the lest interest in what I consider a rather important issue about e-books identification.
upvoted_answer: This is a great question, and I don't have any inside knowledge about how search engines interpret metadata for books. 
  
  I checked the source of several book distributors and found that there's an open graph generator for books. http://webcodetools.com/open-graph-generator/book
  
  Librarything, Smashwords and Harper Row publishers embed ebook info in these tags, and possibly more (but not Amazon). 
  
  I don't know if putting things in the meta tag really counts as giving it semantic meaning though.
  
  Also, it's interesting that I don't see anything human readable on Amazon that might resemble this. 
  
  Dublin core metadata is popular for library cataloguing, but I don't think it really offers useful information for search engines http://wiki.mobileread.com/wiki/Dublin_Core
  http://dublincore.org/documents/dces/
  
  Actually when you input metadata for an ebook in Calibre, it generates dublin core data in the metadata.opf file (and you can edit this metadata by right-clicking the epub in Calibre). DB metadata is required and it typically appears in package.opf. Of course, this  standard doesn't seem to be geared to ebooks, and things like ISBN don't translate well for ebooks.  
  
  While logically it makes sense to have metadata for all the ebook distributors, it's unlikely that ebook distributors would carry metadata on its competitors. Publishers and authors are more likely to benefit from embedding this metadata, but what I've seen so far looks very simple (and gives only one URL). 
  
  I am guessing that while you might be able to do ISBN searches across platforms (even for ebooks), this is not especially useful for ebooks. It sounds like  other than fuzzy searches, there is no direct way for a database to be linked to the same ebook on different ebook distributors.  
  
  These are superficial thoughts, but  I would not be surprised if some kind of solution emerges over the next few years.