To: email@example.com In-Reply-To: "Karen R. Sollins"'s message of Mon, 21 Aug 1995 08:21:18 -0700 <199508211521.LAA09705@lysithea.lcs.mit.edu> Subject: Re: Persistent Documents and Locations From: Larry Masinter <firstname.lastname@example.org> Message-Id: <95Aug22.email@example.com> Date: Tue, 22 Aug 1995 00:31:28 PDT > If I let out a reference to > something for which I have sole responsibility and that I intend to > keep that way, then I have the option of causing that thing to be no > longer available. Et voila! the potential for dangling references. The immovable reader meets the unstoppable author! (Or is it vice versa!) Publishers may wish to keep readers from keeping copies of things, but can they? > If one takes the position that dangling references are a "bad" thing, > one is saying that this sort of situation is a "bad" thing. Either I > can never let out the references or the things can never be withdrawn. I'm trying to avoid unnecessary value judgements. My position is that dangling references are "bad" when they are unwanted by the parties involved. When dangling references are unwanted: * A system of long-term preservation is necessary to prevent dangling references. As long as references are to last longer than the lifetime of the author or copyright holder, some institutional means of preserving the digital objects associated with the information is necessary. * A system of long-term preservation is sufficient to prevent (unwanted) dangling references to digital objects. Presumably the long-term preservation system would have some mechanism for cataloging the things it was preserving. This need not be of any global design or optimization, but merely both satisfy the URN requirements (long-term handle) and also the engineering requirements of the preservation system. Given such a handle, one could use it as or in addition to a reference. I'm not claiming that this will solve all 'dangling reference' problems. Services move as well as digital objects, and objects get updated in ways that finding the latest version of something requires additional infrastructure. And I withdraw the claim that 'naming without preservation isn't useful'. Of course it's useful, and the case where the author doesn't want to relinquish control is just one instance. But it is both necessary and sufficient for solving a class of dangling reference problems, where documents disappear merely because the author stopped maintaining the site.