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The degree to which Content Information and its associated PDI conveys information to a Designated Community is, in general, quite subjective. Nevertheless, it is essential that an Archive make this determination in order to maximize information preservation. Digital Content Information and PDI need adequate Representation Information to be Independently Understandable to the Designated Community. Typically there are multiple Representation Information objects involved, and this is discussed in 4.2.

For example, consider Content Information from a digital set of observations of rainfall, temperature, pressure, wind velocities, and other parameters measured all over the world for a year. This type of information is very extensive and is not usually in a form intended for direct human browsing or reading; but it is in a form appropriate to searching and manipulation by application software. Such content may only be understandable to the original Producers, unless there is adequate documentation of the meaning of the various fields and their inter-relationships, and how the values relate back to the original instrumentation that made the observations. In such specialized fields extra effort is needed to ensure that the Content Information and the Preservation Description Information are understandable to a Designated Community. If the Archive does not have this level of expertise in-house, it may have outside community representatives review the information for Long Term understandability. Otherwise some of the information may be understandable to only a few specialists and be lost when they are no longer available.

Even when a set of information has been determined to be understandable to a particular Designated Community, over time the Knowledge Base of this community may evolve to the point that important aspects of the information may no longer be readily understandable. At this point it may be necessary for the OAIS to enhance the associated Representation Information so that it is again readily understandable to the Designated Community.

As another example, a manuscript’s Content Information may be written in English and therefore its content may be generally understandable to a wide audience. However, unless the purpose for which it was created is clearly documented, much of its meaning may be lost. This ‘purpose’ information is part of its Context and must be provided in the Preservation Description Information.

Software is needed for efficient access to Digital Content Information. However, maintaining Content Information-specific software over the Long Term has not yet been proven cost effective because of the narrow application of such software. The danger of information loss is great when such software is relied upon for information preservation and understanding because it may cease to function under only small changes to the hardware and software environment. This may not be recognized unless there is a vigorous, ongoing, testing and validation program. A related approach is to employ an emulator that maintains a consistent environment for a range of application specific software. A major concern with this approach is the need to upgrade and maintain the emulator over time while ensuring it runs all the application specific software with fidelity, and to do this cost-effectively.

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These wiki pages are licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. Attribute as "Community forum for digital preservation and curation standards http://wiki.dpconline.org/". The content on this wiki represents the opinions of the author and not the Digital Preservation Coalition. This wiki is not associated with ISO, the OAIS Standard or the CCSDS.