What do the numbers in the DOI signify?
A. The DOI has two components, a prefix (before the slash) and a suffix (after the slash). The prefix is a DOI resolver server identifer (10) and a unique identifier assigned to the publisher—for example, the identifier for NPG is 1038 and the entire DOI prefix for an article published by NPG is 10.1038. The suffix is an arbitrary number provided by the publisher. It can be composed of numbers and/or letters and does not necessarily have any systematic significance. Each DOI is registered in a central resolution database that associates it with one or more corresponding web locations (URLs). For example, the DOI 10.1038/ng571 connects to http://dx.doi.org/10.1038/ng571.
