This may be appropriate for some uses but is clearly inadequate for others. If we are to be able to identify all rights owners in a particular piece of content, that may require a far finer degree of granularity of identification, to the level of the individual illustration or quotation from another source. Similarly, if information is to be traded with customers at a level of granularity finer than the 'chapter' or the 'article', then publishers may have compelling marketing reasons for being able to properly identify and keep track of what is being traded. Although each unique identifier system is different, here we'll explore only the AAP's Digital Object Identifier. The number will comprise a Publisher ID and an Item ID which will reside in a DOI Directory Service.
Potential licensees can key a DOI number into a Web-based interface to query the master directory.
Unique identifiers are important for tracking and identifying content within a publishing house and for identifying content during online commerce transactions. But as a standalone intellectual- property management system, the DOI is limited. Browsers or potential licensees will need to know a specific DOI before they can query the master database. If a DOI is separated from the object it identifies, the ability to uncover ownership, rights, and contact information is lost. Digital watermarks require special viewing software for seeing and reading the serial numbers.