5.2 PRESERVATION OF ACCESS AND USE SERVICES
An OAIS may wish to preserve a Consumer access service in the face of changing technology. To delineate some access service preservation issues and provide terminology, this subsection addresses a set of scenarios in the subsections below.
In some cases the supporting tools such as the original access and use mechanisms i.e., Content Data Object [CDO] specific software (referred to as CDO software below) that are not essential for Content Information preservation but are convenient for access, are determined to remain adequate for an extended period. However eventually this support tool CDO software will cease to function as the operating environment changes, or at least cease to function correctly, unless some action is taken. One action is to re-implement that support tool CDO software functionality in the new environment. This has no impact on the preservation of the Content Information.
Another action is to decide that it is too costly to re-implement the support tool CDO software functionality. If there is enough CDO software in this category, it may appear cost- effective to emulate the original environment and provide this as an additional support tool. This also has no effect on Content Information preservation as long as the Structure and Semantic Representation Information are maintained.
In some situations, it may be difficult or impossible to secure the necessary explicit Structure and Semantic Representation Information. In this case the maintenance of operational CDO specific software, which embodies some understanding of the Structure and Semantic Representation Information (the rest typically allocated to the operating environment), may be the only near-term practical option. Such software becomes part of the Representation Information under the Other Representation Information category. Eventually evolution of the operating environment will jeopardize the functioning of the CDO specific software. Either the Content Information will need to be transformed, thus altering both the Content Data Object and the Representation Information and requiring new CDO software for access, or emulation software supporting the original CDO software will be needed. Such emulation software logically becomes an extension of the Other Representation Information as it directly addresses Content Information preservation.
The following matrix shows the various combinations of some of the alternatives discussed above when evolution of the operating environment jeopardizes operational CDO software.
--Please retain original text above for reference. Propose amendments or additions below this line or respond using the Discussion tab above--
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.