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At 16:53 13/06/02 +0100, you wrote: >Am very concerned at hearing that the life of CDs is >limited. And without a copyright waiver does that mean >that libraries holding rare scanned documents cannot >refresh the CDs to preserve the images? The Library of >Congress in Washington reckons that it will 'lose' 90% >of all of its magnetic holdings - video/audio tapes - >in the next 100 years (discounting changes of format >and the fact that machines to play the old formats >might become obsolete). So they are digitising >everything they can. So what it wrong with CDs? Are >they even more fragile than magnetic video tape. The >life of the latter is about 30 years after which the >adhesive holding the magnetic particles onto the >plastic base decomposes into a white dust which clogs >up the heads. What happens to CDs? With commercially produced CDs and CD-ROMs the relective aluminium coating slowly oxidises and/or delaminates from the clear plastic. With CD-Rs and CD-RWs the dyes used are also susceptible to degradation (probably in only a few years ...). More often, CDs and CD-Rs etc 'die' because they get scratched or dirty. Unlike audio recordings on magnetic tape (which progressively loose quality), all digital media are vulnerable to 'all or nothing' data loss - a small amount of damage to critical parts of the CD could mean all the information is unretrievable. Copyright law has been tightened to protect copyright until 80 years after death of the author. This totally frustrates 'reprinting' and the like. With multi-author works (LSJ is an excellent example) in, let us say, 50 years time, there is little chance that all the (by then mostly deceased) authors will have appointed a literary executor and, even if they had, who will know who that person is? More crucially, in 20 years time working CD players will be much rarer than people who can use slide rules are today , as other storage media are already poised to take their place (OK, I accept that 'next generation' DVD players are backward compatable with CDs, but solid state storage - Gigabytes in a 'key fob' - is already a reality). And the software to read the CDs that is so commonplace today will only run on hardware that has been kept working by dedicated specialists in museums ... (in reality HTML is quite likely to be one format that will be supported 'forever'.) Makes maintaining paper-based archives seem easy, doesn't it??? All these complexities of digital archiving have their own discussion lists, although the only one I know is <[log in to unmask]>. British archaeology has its own digital archiving project at York, where excavators pay a flat fee to have their archives 'deposited' and curated - even if this means transferring the data to non-proprietary formats. Hope this helps a little. Bob