In order for electronic publications to be referenced like conventional ones, it is absolutely necessary that their permanence is guaranteed, so that the publication can be retrieved for inspection in the future. We consider two aspects of this permanence: the possibility to access the Hyperguide as a whole at a well-defined and permanent address, and a reliable system for update control. The latter means that it shall always be possible to find out what were the contents of the hyperguide at a particular point in time. The possibility of the electronic medium to successively update the text and keep it current must of course not be lost, but it must be handled in such a way that history can not be rewritten.
This is at the present time a proposal, pending the confirmation of the technical possibilities
The full contents of the LAC Hyperguide may be distributed over several different computer systems (hosts), both in order to keep them closer to the author, and in order to have multiple copies of the same material. Multiple copies may serve several purposes: reliability, reduction of communication costs and delays, etc. However, there is one key address which is the "official" Internet address of the hyperguide as a whole, namely
http://vir.liu.se/hg-lac/
The host name refers to Linköping University, Sweden,
but it is not bound to any particular computer system there:
vir stands for "virtual", and reflects that the
contents can be moved to other computer systems as this
is made necessary over time.
Substructures of the hyperguide should always be referenced using this address. For example, the present segment can be addressed as
http://vir.liu.se/hg-lac/reading/publisher
using the path that is indicated at the top of this page.
However, such references into the structure should be used
with care. See the segment "How to Reference Material in the
Hypermanual".
The other important issue regards update control. This topic is in fact even more crucial for the Electronic Publications Archive (EPA), and will be addressed in that context.
The first step is to structure the archive and the hyperguide in such a fashion that significant updates are documented. We make a distinction between "referencable" and "non-referencable" segments of the guide. Referencable segments are supposed to be updated only when there are significant reasons, and their older versions are retained in archive. Non-referencable segments are not subjected to those restrictions, and their old versions are not guaranteed to be archived. This structuring is taking place already in the present, experimental phase of the development.
The second step will be to transfer the responsibility for the archival part to a separate organizational entity, which can serve as a kind of "notary public" with respect to archival integrity. This step will only be taken when sufficient experience has been gathered with the administration of updates and old segment versions.