The problem of unmaintained or relocated URLs is a major one. In one major collection of around 150 I created in October 1994, only around 80 were still operational one year later. Furthermore, as an author, if you decide to move to a new server or indeed a new institute, it is almost impossible for you to notify everyone who might have linked to you. We all thought URNs were the problem, but for reasons I do not fully understand (expense?) these are not functional yet. However, PURLs are! See e.g. http://purl.oclc.org/net/intercat Here purl.oclc.org is a URL resolver. Register your URL with them (and re-register if it moves) and in theory everyone will continue to be able to find your documents. This is much implication for journals, and all other sorts of permanent or semi-permanent documents. The system is not quite working yet, but it will soon be so! More info when I get it. Dr Henry Rzepa, Department of Chemistry, Imperial College, LONDON SW7 2AY; rzepa@ic.ac.uk via Eudora Pro 2.1.3; Tel (44) 171 594 5774; Fax: (44) 171 594 5804. World-Wide Web URL: http://www.ch.ic.ac.uk/rzepa/ ----- chemweb: A list for Chemical Applications of the Internet. Archived as: http://www.ch.ic.ac.uk/hypermail/chemweb/ To unsubscribe, send to listserver@ic.ac.uk the following message; unsubscribe chemweb List coordinator, Henry Rzepa (rzepa@ic.ac.uk)