DCMIDC Tabular Application Profiles (DC TAP) is a specification from the Dublin Core Metadata Initiative that provides a vocabulary and format for expressing metadata application profiles in simple tables and spreadsheets. By defining a compact set of 12 elements, DC TAP makes it possible for metadata designers to document property constraints, value types, cardinality rules, and structural shapes in a format that is both human-readable and machine-processable.
Background
Application profiles — selections and constraints of metadata properties drawn from one or more vocabularies — have long been central to metadata practice, but their documentation has lacked a standard, interoperable format. The DCMI Application Profiles Interest Group (later Working Group) set out to address this gap by developing a tabular approach that could be created and edited in familiar tools such as spreadsheets and CSV editors.
The DC TAP primer was published as a DCMI Community Specification draft for comment on April 23, 2021, with Karen Coyle as editor and contributions from Tom Baker (DCMI), Phil Barker (Cetis LLP), John Huck (University of Alberta), Ben Riesenberg (University of Washington), and Nishad Thalhath (University of Tsukuba). Development continues in the open on GitHub, where a more recent editor's draft is maintained.
Purpose & Scope
DC TAP addresses metadata practitioners who need to define and share application profiles without requiring specialized tooling or schema languages. A profile created with DC TAP serves multiple functions: metadata creation guidance, validation rule definition, metadata exchange documentation, and mapping support between different metadata sources.
The specification targets any community that creates metadata from open vocabularies, whether in the cultural heritage, library, research data, or web publishing domains.
Key Elements
DC TAP defines 12 elements organized around properties and shapes:
| Element | Purpose |
|---|---|
| propertyID | Identifier of a vocabulary term (required) |
| propertyLabel | Human-readable label for the property |
| mandatory | Whether the property is required (Boolean) |
| repeatable | Whether the property may repeat (Boolean) |
| valueNodeType | RDF node type: IRI, bnode, or literal |
| valueDataType | Literal datatype (typically XSD types) |
| valueConstraint | Specific allowed value(s) |
| valueConstraintType | Type of constraint: picklist, IRIstem, pattern, languageTag |
| valueShape | Reference to another shape in the profile |
| shapeID | Identifier for a group of properties describing a resource |
| shapeLabel | Human-readable label for the shape |
| note | Free-text annotation |
The only required element is propertyID. All others are optional, allowing profiles to range from a simple property list to a fully constrained validation specification.
Shapes and Structure
A distinguishing feature of DC TAP is the concept of shapes — named groups of properties that describe a particular type of resource. For example, bibliographic metadata might define separate shapes for books and authors, each with their own set of properties. Shapes can reference one another through the valueShape element, enabling the representation of relationships between resource types.
Serialization & Format
DC TAP profiles are designed to be stored as CSV (comma-separated values) files, though any tabular format (tab-delimited, spreadsheets) is compatible. Column headers correspond to the 12 element names, and each row represents a single metadata statement. The order of columns is not significant.
Namespace prefixes are documented in a separate table mapping prefixes to full IRIs, following common Linked Data practice.
Governance & Maintenance
DC TAP is maintained by the DCMI Application Profiles Working Group under the Dublin Core Metadata Initiative. The specification, vocabulary declaration, and CSV template are all hosted on GitHub at the dcmi/dctap repository. The working group accepts comments via GitHub issues and the application-profiles-ig mailing list.
Related Standards
- DCMI Metadata Terms — the vocabulary most commonly profiled using DC TAP
- Dublin Core Metadata Element Set — the foundational property set
- ShEx (Shape Expressions) — a more formal RDF validation language that shares the concept of shapes
- SHACL — W3C Shapes Constraint Language, another approach to RDF validation