As of April 2011, the DOI System has now assigned over 51 million DOI names. The DOI System currently is used by over 4,000 naming authorities (assigners). Around 100 million DOI resolutions are made each month.
The DOI System released this information in their April News. DOI stands for Digital Object Identifiers and The DOI System was developed by the International DOI Foundation (IDF).
In addition, the April News reported that Digital Object Identifiers assigned by CrossRef are now enabled for use in linked data applications. A significant advantage of applying linked data principles and technologies to DOI-registered material is that it is curated, value-added data, which is managed, corrected, updated and consistently maintained by registration agencies. Aaah, worthy data; always a good thing.
Melody K. Smith