Key Facts on Digital Object Identifier System

DOI = Digital Object Identifier
IDF = International DOI Foundation (operating and governing organisation): https://0-www-doi-org.pugwash.lib.warwick.ac.uk/
RAs = DOI Registration Agencies (= members of IDF offering the system to customers who wish to assign DOI names)

Foundation launched to develop system in 1998. First applications launched 2000
Currently used by well over 5,000 assigners, e.g., publishers, science data centres, movie studios, etc.
Approximately 275 million DOI names assigned to date
Over 155,000 DOI name prefixes within the DOI System
Approximately 1 billion DOI resolutions per month
DOI names are assigned by multiple RAs worldwide
Over 30 million shortDOI links to DOI names are in use
Initial applications are simple redirection — a persistent identifier
More sophisticated functionality available, e.g., multiple resolution, data typing
International Standard: ISO 26324, Digital Object Identifier System, 1 May 2012 (available from the ISO Store)

Digital Identifier of an Object (not “Identifier of a Digital Object”)
Object = any entity (thing: physical, digital, or abstract)
- Resources, parties, licences, etc.
Digital Identifier = network actionable identifier (“click on it and do something”)
Generic framework
Initial focus on entities was documents/media e.g., articles, data sets
- Now also moving into parties and licences
- Extending to other sectors
Extensible by design to any sector: not intended as a publishing-only solution (digital convergence)
International coverage

Provides an actionable, interoperable, persistent link
Actionable – through use of identifier syntax and network resolution mechanism (Handle System®)
Persistent – through combination of supporting improved handle infrastructure (registry database, proxy support, etc) and social infrastructure (obligations by Registration Agencies)
Interoperable – through use of a data model providing semantic interoperability and grouping mechanisms

IDF = operating and governing organisation
Provides the social infrastructure
- e.g., obligations for persistence, back-up, in event of failure, etc.
Proven model: successfully transitioned the management of persistent identifiers between different registrants and between different RAs
US “Not for profit” open membership (with membership fee)
Federation of Registration Agencies makes up majority of the IDF
Elected Board
No full time staff (contracted outsourced functions)

IDF receives membership fees from RAs, contracts technical operator
RAs are members of IDF and pay a fixed fee per year
Costs of operating the system are divided across RAs so that IDF is cost-neutral
Assigners are customers of RAs
RAs might have their own existing numbering scheme, existing communities etc. – which can be integrated with a DOI Application not replaced by it.
RAs are autonomous independent bodies. They offer services to assigners using DOI names
- RAs’ business model with their customers is entirely autonomous
- RAs only obligation to IDF is a licence/operating agreement
- RAs may choose to put DOI names “under the hood”
Some RAs are commercial; others are themselves member communities

Handle System: persistent identification in digital networks
Vocabulary Mapping Framework: data dictionary methodology for associated metadata
Both used elsewhere: aim was not to re-invent the wheel

ISO 26324, Information and Documentation — Digital Object Identifier System (2012)
Mechanism for, and emphasis on, enabling re-use of other existing identifier schemes, e.g., ISBN; see “DOI System and Standard Identifier Schemes”.

1996 proposal from the three major international publishing trade associations to develop infrastructure for digital publishing;
Need in the digital supply chain for an equivalent of the analogue bar code: migration from analogue to digital networked content cannot rely on URLs as identifiers (e.g., due to “linkrot”: “404 not found”)

Strong focus on interoperability and on working with existing and new schemes; technical, syntactic, and semantic interoperability
Adopt existing proven components

IDF owns DOI®, a registered trademark for the system
IDF does not have any patents (or patent applications) on DOI System
IDF collectively licences appropriate technology from suppliers on behalf of members
Patent Policy in place
All RAs must sign RA agreement re use of IDF System
IDF is a participant in related projects

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