The website of the American Numismatic Society (ANS) produces useful results for URLs that are similar to http://www.numismatics.org/dnid/numismatics.org:1977.158.462 . In this case, the ANS server redirects to the html representation of information about the object in the ANS collection with the accession number 1977.158.462. This is implemented using the Rewrite directive of the Apache 2 webserver.

The fact that the ANS site can directly accept DNIDs as unambiguous identifiers of objects in its collection means that DNIDs in this context can be “bidirectional” and “author activated”. What does this mean? Consider a case in which a web-site author put the following html into a page: <a href=“http://www.numismatics.org/dnid/numismatics.org:1944.100.39359”;numismatics.org:1944.100.39359</a> . When a search engine such as Google crawls the author's page it will follow that link to the ANS record for that object. This means that the DNID is “author activated” in that it is the agency of the author that has made the ANS object accessible to search engines.

When a user views that record in the ANS database, perhaps by initiating a search such as "coins of the roman emperor Claudius of type 'BMC.79'", and clicks on “expand” to access further information, s/he will see the link “Find pages that refer to this ANS object”. The underlying URL for this link is “http://www.google.com/search?q=numismatics.org:1944.100.39359” . Note that the “q” parameter has the value “numismatics.org:1944.100.39359”. That string is likely to be unique so that a page with that string will appear in the search results. The ability of ANS objects to find pages that use DNIDs to refer to them is what makes DNIDs “bidirectional”.