Again wisely, they have therefore tried to propose an extensible architecture that could be added to by particular communities. We should recognise and accept that art historians, say, will have special and different requirements from, say, mathematicians, and vice versa. But what we should resist as far as possible is the situation where metadata can meet the needs for, say, resource discovery perfectly but does nothing for preservation or rights management - and vice versa. Of course this makes life difficult - it is hard enough to meet one of these major interests but that should not stop us trying. The problem of the fragility of digital media.
All digital media have a far shorter 'shelf-life' than paper.
The problem of software and hardware obsolescence. Several authors point out that 2 is a more intractable problem than 1. Different authors use some of these terms differently but my preferred way of viewing the main solutions is as a spectrum which goes from the simplest to the most complex. See figure 1. Is not a problem at the time in question.