Glossary

An application profile is a metadata design specification that uses a selection of terms from multiple metadata vocabularies, with added constraints, to meet application-specific requirements. In the Dublin Core™ context, application profiles are ideally based on, or compatible with, vocabularies defined in RDF.

A Competency Index is a set of topically arranged assertions of the knowledge, skills, and habits of mind required for professional practice in a given area of practice. DCMI's Linked Data Competency Index, for example, provides an overview, or map, of the Linked Data field both for independent learners who want to learn Linked Data methods and technology, and for professors or trainers who want to design and teach courses on the subject.

Concept Scheme is basically a synonym for Ontology, though concept schemes are most commonly associated with Simple Knowledge Organization System (SKOS), a data model for knowledge organization systems that was designed for maximum semantic simplicity.

The DCMI Abstract Model ("DCAM"), developed between 2003 and 2007 and now considered superseded by newer models, described the design of metadata records in terms of structural components, such as Descriptions, Statements, Properties, and (literal or non-literal) Values, in order to enable structural validation of RDF-based metadata.

The Properties, Classes, Vocabulary Encoding Schemes, and Datatypes declared and maintained by the Dublin Core™ Metadata Initiative are collectively referred to as DCMI Metadata Terms. Property, Class, and Datatype (aka Syntax Encoding Scheme) are defined exactly as in RDF, while a Vocabulary Encoding Scheme is equivalent to the identifier for a SKOS Concept Scheme.

The 2008 draft "Description Set Profiles: a constraint language for Dublin Core™ application profiles" (DC-DSP) provided a language for specifying constraints on the structural components of a Description Set as defined by the DCMI Abstract Model. DC-DSP expressed sets of constraints as "templates" against which RDF graph-based instance metadata (records) could be matched (validated) - an idea achievable today using the newer technologies, inspired in part by DC-DSP, Shape Expressions Language (ShEx) and Shapes Constraint Language (SHACL).

Domain Includes and Range Includes are used to suggest classes to which, respectively, the subject or object of an RDF statement may belong. In contrast to formal domains and ranges, domain and range includes are less about enabling logical inference than about helping users understand how a given property is intended to be used. Drawing a lesson from the successful Schema.org initiative, the DCMI Usage Board decided in 2018 to soften many of the formal domains and ranges added in 2008 to domain and range includes.

Domains and ranges are specified in the definitions of RDF properties in order to enable inferences about the things described using those properties. As defined in W3C's RDF Schema specification, a domain is the class to which the subject of an RDF statement using a given property belongs, and a range is the class of its object (value). Domains and ranges, which were added to the definitions of numerous DCMI properties in 2008, were largely changed by the DCMI Usage Board in 2018 to the less rigidly logical "domain includes" and "range includes".

"The Dublin Core™", also known as the Dublin Core™ Metadata Element Set, is a set of fifteen "core" elements (properties) for describing resources. This fifteen-element Dublin Core™ has been formally standardized as ISO 15836, ANSI/NISO Z39.85, and IETF RFC 5013. The core properties are part of a larger set of DCMI Metadata Terms. "Dublin Core™" is also used as an adjective for Dublin Core™ metadata, a style of metadata that draws on multiple RDF vocabularies, packaged and constrained in Dublin Core™ application profiles.

When the DCMI Usage Board was founded in 2001, it formulated DCMI Grammatical Principles as a point of reference for vocabulary maintenance decisions. The principles, which followed concepts, that had emerged in early Dublin Core™ workshops, such as Element, Qualifier, and Encoding Scheme, were superseded in 2005 by the DCMI Abstract Model, which was based more explicitly on RDF.

The Dumb-Down Principle, which entered Dublin Core™ discourse in 1998, denoted a principled way of viewing a complex metadata description through the lens of a simpler representation, typically Simple Dublin Core.

The Encoding Scheme entered Dublin Core™ discourse at a 1997 workshop in Canberra, Australia. As originally defined, a Scheme was a Qualifier that "specifie[d] a context for the interpretation of a given element". In 2000, the encoding scheme was differentiated into the Syntax Encoding Scheme and Vocabulary Encoding Scheme.

Metadata harmonization can be defined as "the ability of two or more systems or components to exchange 'combined metadata' conforming to two or more metadata specifications, and to interpret the metadata that has been exchanged in a way that is consistent with the intentions of the creators of the metadata" (Mikael Nilsson).

In contrast to "metadata harmonization", metadata interoperability is "the ability of two or more systems or components to exchange descriptive data about things, and to interpret the descriptive data that has been exchanged in a way that is consistent with the interpretation of the creator of the data" (Mikael Nilsson).

The DCMI Namespace Policy, in 2001 among the first such policies of its kind to be articulated for any vocabulary, declares the principles by which DCMI Metadata Terms are identified and published as an RDF vocabulary. The namespace policy declares guidelines for maintenance changes to DCMI terms: The correction of editorial errata (e.g., updated URLs pointing to documentation external to DCMI) result in no changes to DCMI term URIs, while semantic changes judged likely to have a substantial impact on machine processing are supposed to trigger the creation of new terms with new URIs.

The One-to-One Principle says that conceptually distinct entities, such as a painting and a digital image of the painting, should be described by conceptually distinct descriptions. The principle was formulated in the early years of Dublin Core™ in order to draw attention to, and challenge, the widespread practice of creating metadata that pragmatically conflated elements descriptive of conceptually distinct resources into a single record.

An ontology, according to one famous definition from 1992, is the "specification of a conceptualization" - an abstract, simplified view of the world represented for purposes ranging from knowledge sharing to decision-making. While ontologies are commonly assumed to be semantically complex, with rich sets of relationships between its concepts and axioms designed to support sophisticated inferencing, there is no inherent limit to how simple an ontology may be. Indeed, the key ontologies of the Finto, the Finnish thesaurus and ontology service, are actually SKOS concept schemes, and the Dublin Core™ vocabulary itself is sometimes referred to as an ontology.

Open World Design accepts that information exists in a global context that is evolving in unpredictable ways and avoids assuming that interoperability with future, possibly unanticipated sources can be more than partial. Open World Design stands in contrast to the Closed World Design of traditional IT environments, in which data is carefully controlled, with document formats and database schemas optimized for specific applications. Loosely specified vocabularies such as Dublin Core, when used with generic underlying models such as RDF, provide a good technological basis for Open World Design.

Following a landmark workshop on RDF validation in 2013, two languages have emerged for describing the "shape" of graph structures for the purpose of validating RDF data. The Shape Expressions Language (ShEx) and Shapes Constraint Language (SHACL) provide languages for expressing constraints against which graphs of RDF triples can be compared. These languages support the expression of a Dublin Core™ application profile in a manner that can directly be used for validating metadata based on the profile.

In the late 1990s, following the development of Dublin Core™ qualifiers, the term Simple Dublin Core™ was coined to denote metadata about a single resource, using only the fifteen properties of the Dublin Core™ Metadata Element Set, with string values, and without qualifiers.

Syntax Encoding Scheme is a DCMI-specific synonym for RDF Datatype. An RDF Datatype indicates that a given literal represents a resource of a given type, such as a Gregorian calendar date, Boolean value, integer, or natural-language character string. Datatypes are identified by URI and associated with literals using RDF syntax.

In Semantic Web usage, Vocabulary is a near-synonym for Ontology though "trend is to use the word ontology for more complex, and possibly quite formal collection of terms, whereas vocabulary is used when such strict formalism is not necessarily used or only in a very loose sense." Whatever else they might be called, DCMI Metadata Terms, the AGROVOC concept scheme, and the Bibliographic Ontology (BIBO) are also vocabularies.

Vocabulary Encoding Scheme (VES) is a DCMI-specific synonym for the identifier of a SKOS Concept Scheme. Starting with the Dublin Core™ Qualifiers specification of 2000, DCMI coined VES URIs as a way to indicate the source of string values from published controlled vocabularies such as the Library of Congress Subject Headings (LCSH). For example, the string value Textile design--China--History could be marked as coming from LCSH by tagging it with the DCMI-coined VES URI http://purl.org/dc/terms/LCSH. With the widespread conversion of controlled vocabularies such as LCSH into SKOS after 2009, the Vocabulary Encoding Scheme has become less relevant as a type of metadata term.