A URL standard that is focused on resolving object descriptions (usually bibliographic citations). The resolver should take the user's context into account. A database can export an OpenURL link for an item not available in the database, and a resolver can search the other databases available at the user's location to see if the item is available online, requestable through ILL, etc.
The OpenURL 1.0 standard provides for linking between an "identifiable resource" and an "appropriate service", making it much more powerful than the (more widely supported) 0.1 standard. The resource and service are translated into the "appropriate" URL for the underlying system. For example, all (API-A) functionality in Fedora could be accessed by treating objects as resources and disseminators as services. Placing an OpenURL layer on top of Fedora would allow it to interact seamlessly with other types of repositories.