Sir

Several Correspondences, including 'Give south Indian authors their true names' (Nature 452, 530; 2008) and 'Name variations can hit citation rankings' (Nature 453, 450; 2008), have illustrated difficulties in identifying authors and their papers, citations and h-index.

In an academic world in which decisions on promotion and funding often depend on the applicant's scientific impact, an incorrect publication or citation record in an online database can be very inconvenient. Scopus and Thomson's Web of Science, which make available abstract and citation databases, acknowledge the issue and have come up with solutions: the Author Identifier and ResearcherID, respectively.

These systems assign an identifying code to each author. Unfortunately, a single author can have more than one Author Identifier in Scopus (I am cryptically known as 7006716603 and 16551750300). And as only invited researchers can register for a number, ResearcherID is not yet used as a unique author key in the Web of Science — making it difficult to differentiate me from a highly cited ecologist from the Netherlands, despite the 'Distinct Author Sets' feature.

If it is possible to have DOIs for objects (or, so they say, enough IPv6 addresses for every molecule on Earth), why is it so difficult to implement DAIs for authors?