Permanent URLs: a means of perpetuating Web addresses

Obsolescence of URLs is a problem that hopefully will be identified by resources published on the Web. Between the reorganisations of the branching of sites and domain names for which the subscriber ceases to pay when the corresponding site, protected within a free provider, continues to exist, it is very difficult to maintain an up-to-date directory of URLs. Unless and until URNs (Uniform Resource Names) become a reality, there will be no completely effective solution to the problem. This article expounds an interim means, proposed in 1996 by the Research Department of OCLC, to simplify the task of bringing URLs up to date, which has the great advantage of being at the same time free and simple to implement: persistent URLs, or PURLs.