PREMIS Controlled vocabularies Rebecca Guenther Sr. Networking & Standards Specialist, Library of Congress PREMIS Implementation Fair Vienna, Austria Sept. 22, 2010

Use of controlled vocabularies in PREMIS  Many semantic units include a data constraint: “Value should be taken from a controlled vocabulary”  Most have “suggested values”  There is not currently a way to enforce selection of a controlled value  LC is using the Authorities and vocabularies service at id.loc.gov to formalize them

Example: messageDigestAlgorithm

Reasons for developing a web service for vocabularies  Facilitate development and maintenance process for vocabularies  Make controlled lists openly available  Provide comprehensive information about controlled terms  Experiment with semantic web technologies and linked data  Expose vocabularies to wider communities

“Linked Data”  A feature of the “Semantic Web” where links are made between resources  Goes beyond hypertext links (i.e. between web pages) but between any kind of object or concept  From Wikipedia: "a term used to describe a method of exposing, sharing, and connecting data via dereferenceable URIs on the Web” Users can use links to find similar resources and aggregate results

About SKOS Simple Knowledge Organization System RDF application used to express knowledge organization systems such as classifications, thesauri, taxonomies, and the concepts within Allows distributed, decentralized management of KOS through Linked Data- inspired application. All concepts and schemes require a URI Works with PREMIS OWL ontology

Using controlled vocabularies in PREMIS  Semantic units that specify a controlled vocabulary: realized as “concept scheme”  Each value: realized as SKOS instance  Implementers add their values within a concept scheme  Mechanism to import the values into the PREMIS XML schema to enable validation  A concept in multiple standards is established for broad usage in a concept scheme, e.g. messageDigestAlgorithm/CHECKSUMTYPE

Introducing id.loc.gov Library of Congress Authorities & Vocabularies service: Allows both human-oriented and programmatic access to LC-promulgated authorities and vocabularies. First offering was Library of Congress Subject Headings in April 2009 Additional vocabularies added April 2010

Vocabularies currently available  Cryptographic Hash Algorithm  Preservation events  Preservation level role Demo:

Additional vocabularies to be added  Most semantic units that suggest a controlled vocabulary  Will not include those that require local vocabularies  Some that will be included: formatRegistryRole inhibitorType, inhibitorTarget storageMedium environmentPurpose, environmentCharacteristics Hardware and software type relationshipSubType Rights: rightsBasis, copyrightStatus, act  Need to look at generic names and overlaps with other metadata schemes, e.g. Agent roles (linkingAgentRole in Events and Rights) Content location type (METS LOCTYPE) Values for act under rightsGranted vs. event type

Next steps  Consider overlaps and consult other maintainers of controlled vocabularies where necessary  Editorial committee will review values and definitions  Feedback from PIG  Finish RDF/SKOS markup and bring into database  Make available for use