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Quantities, Units, Dimensions and Types (QUDT) Ontology Version 1.1

The QUDT, or 'Quantity, Unit, Dimension and Type' collection of ontologies define the base classes properties, and restrictions used for modeling physical quantities, units of measure, and their dimensions in various measurement systems. The goal of the QUDT ontology is to provide a unified model of, measurable quantities, units for measuring different kinds of quantities, the numerical values of quantities in different units of measure and the data structures and data types used to store and manipulate these objects in software. This OWL schema is a foundation for a basic treatment of units.

Ontology Metadata

QUDT Schema Catalog Entry

Catalog Entry

An 'Attribution' specifies how credit should be given when citing the creators of a piece of work. Attribution must use the specified attribution text and optionally use logos that are provided in the attribution details below., with the names of points of contact.

Attribution text should be stated as follows:

"The QUDT Ontologies are issued under a Creative Commons Attribution Share Alike 3.0 United States License. Attribution should be made to NASA Ames Research Center and TopQuadrant, Inc."

NASA ARC Attribution

TopQuadrant attribution

Governance [qudt:QUDT-Governance]

Governance concerns how an artifact is provisioned and managed over its lifecycle. Governance also concerns the status tracking and processes that need to exist on information objects and services for a successful initiaitve, mission, program, or project. Such governance needs to outline the relationships between all internal and external groups involved, describe the proper flow of information regarding to all stakeholders, ensure the appropriate review of issues encountered and ensure that required approvals and direction are obtained at each appropriate stage.


Provenance specifies the origin or source of some artifact. The primary purpose of provenance is to capture the time, place, and if appropriate the person responsible, for the creation, production or provisioning of The artifact. Provenance also captures a record of how a version may have been superceded by another version of the artifact.


Pedigree captures aspects of an artifact that have to do with maturity, quality, salience, and accredidation.