Introducing Significant Properties

Stephen Grace and Gareth KnightCentre for e-Research

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Overview of KeepIt session

•Introduction to Significant Properties•InSPECT methodology•Practical exercise in object analysis•Practical exercise in stakeholder analysis

•Implementing SPs in an archive•Summary

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Why Significant Properties?

“The fundamental challenge of digital preservation is to preserve the accessibility and authenticity of digital objects over time and domains, and across changing technical environments”

Wilson, 2008If we change something in order to keep it safe, how do we know we can trust the results?

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Significant Properties timeline

•1999 Clifford Lynch– canonicalisation•1998-2002 CEDARS – significant properties

– “those components of a digital object deemed necessary for its long-term preservation”

•1999-2003 CAMiLEON – significant properties– “those properties of digital objects that affect their

quality, usability, rendering, and behaviour”

•2002 Thibodeau – essential properties or characteristics

cont/

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Significant Properties timeline

•2008 InSPECT – significant properties– “the characteristics of digital objects that must be

preserved over time in order to ensure the continued accessibility, usability, and meaning of the objects”

•2008 PLANETS – Plato utility analysis and XCL•2009 Dappert/Farquhar – significant characteristics

– “custodians must focus their attention on preserving the most significant characteristics of the content, even at the cost of sacrificing less important ones”

•2009 Todd – significant properties

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Authenticity, integrity, viability

“the characteristics of digital objects that must be preserved over time in order to ensure the continued accessibility, usability, and meaning of the objects”

•Authenticity – is this what it purports to be?

•Integrity – is this complete and unaltered?

•Viability – is this suitable for its audience (aka Designated Community)?

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Representation Information in OAISRepresentation Information consists of:

•Structure information thatdescribes the encoding schemein which data is stored, e.g.format, encoding algorithm•Semantic information thatindicate how the values are to beinterpreted. E.g. documentationthat indicates how numericvalues in a CSV or tab-delimitedformat must be interpreted.

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Interpreting SPs in abstract

Source Process PerformanceIn te rp re ted

v iaY ie lds

NAA Performance Model

OAIS Reference Model

Data ObjectRepresentation

InformationInformation

ObjectIn te rp re tedus ing

Y ie lds

E ncod ingP rope rties

S ignif icantP rope rties

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Interpreting SPs in practice

Source Process PerformanceIn te rp re ted

v iaY ie lds

NAA Performance Model

data

=

informationcontent

computer

+

OS

+ +

application

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Significant Property types• Content: conveys information, not necessarily human readable• Context: background information on technical and business environments to which the digital objects relate• Rendering: how the content of the object appears or is recreated, e.g. audio or visual• Structure: component parts of the object and how they relate to each other• Behaviour: functionality that is intrinsic to an object

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Compare and contrast

Info rm ation O b je c t

Manife s tation 1

p rop e rty 1 ... p rop e rty np rop e rty 2

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Compare and contrast

Info rm ation O b jec t

Manifes tation 1

P rope rty 1 ... p rope rty n

Manifes tation 2

p rope rty 2

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SPs used in digital preservation•Document technical properties

•Describe intellectual entities

•Determine preservation priorities

•Measure the success of transformations