BISG Paper on Identifying Digital Book Content
BISG and BIC have published a discussion paper called "The identification of digital book content" - http://www.bisg.org/docs/DigitalIdentifiers_07Jan08.pdf. The paper discusses ISBN, ISTC and DOI amongst other things and makes a series of recommendations which basically say to consider applying DOI, ISBN and ISTC to digital book content. The paper highlights in a positive way that DOI and ISBN are different but can work together (the idea of the "actionable ISBN" and aiding discovery of content). However, it doesn't go into much depth on any of the issues or really explain how all these identifiers would work together and the critical role that metadata plays.
Nevertheless it's great that the paper has been put forward as a discussion document - CrossRef plans to respond and be part of the ongoing discussion in this area.

Comments
As Ed points out, the question of metadata is a critical one. The BISG paper makes the following comment:
In many cases, the DOI will work alongside and in combination with an ISBN, and many publishers may wish to include an element of intelligence in the otherwise free-style DOI syntax by incorporating the ISBN.
I think this is missing the point. The purpose of an identifier is to uniquely refer to a (digital) object within a domain (e.g., within the set of all ISBNs or within a DOI prefix) and to relate that identifier to valuable, actionable information about the object (i.e., authoritative metadata).
Therefore, I think a slightly different approach is called for. Instead of talking about which identifier(s) will work best, the stakeholders (publishers, consumers, intermediaries, etc.) should first answer these questions:
(1) What is it that we are trying to identify? Is it an intellectual property (the stated purpose of the DOI), a sellable product (the de facto purpose of the ISBN), the method of sale (raised in the BISG paper), or more?
(2) Once we know what we are trying to identify, what is the information that must be recorded to support this (digital) object in the supply chain? (And related questions: Who will record it? Where?)
Finally, I would suggest that it is not just information about the objects themselves, but also the relationships between objects that is important.
Kevin Cohn
Product Director, Atypon
Posted by: Kevin Cohn | January 14, 2008 04:09 PM