watermarking, digital signatures, encryption, digital time stamping, audit trails, controlled custody, and trusted repositories (Authenticity, 1999; NSF-DELOS Working Group on Digital Archiving and Preservation, 2003, p.6).
The National Library of Australia’s Digital Preservation Issues Group has also investigated significant properties, defining them in relation to four categories of desired functionality of digital objects that it wishes to preserve: 1) full dynamic/interactive functionality, 2) look/sound and feel, 3) intellectual content, and 4) description of what was (e.g. metadata for an object that no longer exists). Both the National Library’s experience and that of Hedstrom and Lee suggest that further research is required to ascertain significant properties for specific types of digital materials in relation to their use by particular commu- nities (Hedstrom and Lee, 2002, p.223).
The idea of access to digital materials being analogous to a performance is gaining currency. Thibodeau tells us:
It is necessary to recognize that, strictly speaking, it is not possible to preserve an electronic record. It is only possible to preserve the ability to reproduce an electronic record. It is always necessary to retrieve from storage the binary digits that make up the record and process them through some software for delivery or presentation. Analogously, a musical score does not actually store music. It stores a symbolic nota- tion which, when processed by a musician on a suitable instrument, can produce music. Presuming the process is the right process and it is executed correctly, it is the output of such processing that is the record, not the stored bits that are subject to processing (Thibodeau, 2000, p.1).
It is described in the UNESCO Guidelines.The idea is simple; the application of the same software and hardware to the same digital materials should create a
‘presentation or performance’ that is the same every time. For preserved digital materials, their essential elements are presented during a performance some- time in the future: ‘copying data from carrier to carrier, and providing the right tools to recreate the intended performance will preserve continuity of access to most digital objects’. This apparently simple model is, however, rather more complex in practice:
it may be hard to define the performance that must be re-presented; it is usually difficult to work out what tools are needed once the original ones have been lost; the tools themselves typically rely on other tools that also may have been superseded; and it may be difficult to find tools that will create the required performance in a reliable, cost-effective and timely way, especially in the context of many thousands, millions or more of digital objects. Despite such underlying complexities, the performance model helps in recognising what digital preservation programmes must aim for: the best means of re-presenting what users needs to access (UNESCO, 2003, p.36).
An Australian digital preservation specialist interviewed in 2004 noted the National Archives of Australia’s view of performance and essence:
issues like look and feel . . . are significantly less important, because we can demonstrate to you that if we show you the same Word document on a different operating system, it can actually look different. If we show it on a different machine which has different fonts installed, it will look
92 What Attributes of Digital Materials Do We Preserve?
different. If I alter the page setup, or even on different machines with the same page setup, you’ll get a different pagination, and if you’ve got an automatic footer with a page number in it, it will automatically change that pagination for you, and it won’t be apparent to you that the pagination has changed. So a lot of that we have actually defined as being ephemeral or circumstantial aspects of the performance of the record in a particular situation . . . is not particularly relevant. I suppose if we got down to a very fine detail we might at certain points sort of say, well we have to say that because this record is a very important record and it matches let’s say a hard copy record, then it really needs to be viewed with this sort of pagination and that sort of thing, but generally we don’t get down to that level of detail and we would regard that as an extremely exceptional sort of thing to have to do. We’ve defined most of these essence characteristics, in practice we define them by defining the schema for the particular elements.
What this boils down to is that for the materials being preserved we need to understand the characteristics that they embody, and the minimum set of these characteristics that need to be maintained in order to recreate the materials in the future. As well as needing to preserve the physical object (the physical form that carries the bit-stream) it is necessary to preserve the logical object (the computer readable code) and the conceptual object (‘the performance presented to a user’ (UNESCO, 2003, p.36)) that is meaningful to the human user. However, we also need to envisage the digital object as ‘bundles of essential elementsthat embody the message, purpose, or features for which the material was chosen for preservation’ (UNESCO, 2003, p.36). Not all of the elements that make up a digital object are equally important in recreating the conceptual object.
It is also necessary to understand the needs of the community of users for whom digital materials are being preserved. ‘Community’ can be as closely defined as a specific organization or discipline group, or as extensive as ‘the general public’. Their needs determine the kind of material selected for preser- vation and the levels of authenticity required. ‘Essence’, ‘significant properties’, or ‘essential elements’ of the materials selected are defined in relation to the community’s requirements. For example, if the community is one where value is placed on the authenticity of records of transactions, that is their evidential value is high, then a lot of attention must be paid to maintaining the integrity of those records: ensuring that any alterations made to them are carried out only by authorized personnel and are appropriately documented, or that the records are preserved in an unalterable (read-only) form (UNESCO, 2003, p.77).
However, some communities will not require that authenticity be proved to this extent. ‘Ultimately, preservation programmes must decide how much to invest in ensuring that the authenticity of material in their care can be trusted, bearing in mind that object identity and data integrity are fundamental responsibilities’
(UNESCO, 2003, p.114). An Australian example of a community’s response to the challenges of authenticity can be seen in the Authenticated Electronic Editions project. This addresses the needs of textual editing scholars who require
‘maintenance of the integrity of the core text while it is being proliferated, trans- lated across platforms, manipulated, supplemented and analysed.’ To achieve this, the project has developed JITM (Just In Time Markup) (Australian Scholarly Editions Centre, 2001).
1111 2 3 4 51 6 7 8 9 10 1 2 3111 4 5 6 7 8 9 20111 1 211 3 4 5 6 71 8 9 30111 1 2 3 4 5 6 7 8 9 40111 1 2 3 44 45 46 47 48 49 50111
Authenticity 93
The UNESCO Guidelinessuggest some questions to be posed in deciding on essential elements to preserve:
Further elaboration of the example of e-mails, used in the previous chapter and earlier in this chapter, serves to illustrate some points about preserving authen- ticity. Authenticity in this case ensures the trustworthiness of the e-mail as a record of a transaction. An authentic record is ‘one that can be proven a) to be what it purports to be, b) to have been created or sent to the person purported to have created or sent it, and c) to have been created or sent at the time purported’ (Millar, 2004, p.4). For an e-mail to be considered an authentic record, it must be demonstrated that it has not been changed or corrupted, and that it was created by a particular person. This is achieved by ‘describing and preserving the original context of the records and by maintaining a chain of unbroken custody’ (Digital Preservation Testbed, 2003, p.15). Changes are acceptable as long as they do not alter the original meaning of the e-mail.
E-mails can be considered as consisting of five characteristics:
• context (‘the environment in which the digital record is made’)
• content (‘the body of the record, regardless of structure, colour, position or font’)
• structure (‘the structure as it was originally made and reproduced on the screen’)
94 What Attributes of Digital Materials Do We Preserve?
• For whom should this material be kept? Do they have specific
expectations about what they will be able to do with the material when it is re-presented?
• Why are the materials worth keeping? What gives them the value that warrants the trouble of preserving them? Is that value associated with evidence, information, artistic or aesthetic factors, significant innovation, historic or cultural association, what a user can make the material do or do with the material, culturally significant characteristics?
• Is the value tied to the way the material looks? (Would it be lost or significantly degraded if the material looked different?)
• Is the value tied to the way the object works? (Would it be lost if
particular functions were removed? Or if particular functions happened at a different speed or required different keystrokes?)
• Is the value tied to the context of the material? (Would it be lost if links embedded in the material did not work? Or if a user could no longer see evidence that connected the material with its original context?)
• Is it possible to distinguish between elements within each of these areas?
For example, would advertising banners be considered an essential part of the way the material looked? Would some navigation elements or display functions be needed but not others?
• If it is difficult to define what needs to be maintained, it may be easier to consider the impact of an element not being maintained, and to look for functions or elements that are definitely not needed.
Figure 5.2 Deciding on Essential Elements (From UNESCO, 2003, pp.78–79)
• appearance (‘the final presentation, what the records looks like when it appears on the screen’)
• behaviour (‘the interactive characteristics of a records; that which enables us to manipulate and use the record so that new and extra content is displayed’) (Digital Preservation Testbed, 2003, pp.14–16).
For e-mails, however, it could well be decided that it is only the content informa- tion that users require – ‘the name and address of the sender, subject, date and time, recipients, and the message, in a standardised structure with only the most simple of formatting’ (UNESCO, 2003, p.77).
Clausen provides another example, of digital objects harvested from the web.
He identifies five aspects of ‘preservation quality’ – readability, comprehensi- bility, appearance, functionality, and ‘look and feel’ – and gives examples of how these might be applied to a range of digital objects commonly encountered on the web (Clausen, 2004, pp.8–10). A third example, provided by an Australian digital preservation specialist interviewed in 2004, was of the Perseus web site (www.perseus.tufts.edu). He commented that ‘the way the site is laid out, the way things relate to each other, I would have thought was sufficiently signifi- cant to warrant preservation apart from the actual content’. The difficulty of one aspect of this decision was noted: ‘quite how one generalizes from that into a wider set of principles is a harder thing to try to come to terms with’.
More research into authenticity and its requirements in the digital world is required, although establishing these will be no easy task, as the authors of a CLIR publication emphasize (Authenticity in a Digital Environment, 2000). In the opinion of the NSF-DELOS Working Group on Digital Archiving and Preservation, the digital preservation research agenda includes research into tools that allow future users of digital materials to determine whether they are authentic (NSF-DELOS Working Group on Digital Archiving and Preservation, 2003, p.vii). We need a working definition of authenticity, closer definition of significant properties and a clearer understanding of how these significant prop- erties affect use and access of digital materials, knowledge of how much change is acceptable before the authenticity of digital materials is compromised, among other things (Kerry, 2001, p.7). We also need strong legislative, organizational, and policy frameworks for managing digital records, and stronger technical and operational standards (Millar, 2004, p.8).