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QUDT Quantity Ontology Version 1.1

The 'Quantity' Ontology provides a schema for defining quantities. A quantity is a measure of an observable phenomenon, that, when associated with something, becomes a property of that thing; a particular object, event, or physical system. A quantity has meaning in the context of a measurement (i.e. the thing measured, the measured value, the accuracy of measurement, etc.) whereas the underlying quantity kind is independent of any particular measurement. Thus, length is a quantity kind while the height of a rocket is a specific quantity of length; its magnitude that may be expressed in meters, feet, inches, etc. Or, as stated at Wikipedia, in the language of measurement, quantities are quantifiable aspects of the world, such as time, distance, velocity, mass, momentum, energy, and weight, and units are used to describe their measure. Many of these quantities are related to each other by various physical laws, and as a result the units of some of the quantities can be expressed as products (or ratios) of powers of other units (e.g., momentum is mass times velocity and velocity is measured in distance divided by time).

Ontology Metadata

QUDT Quantity Schema Catalog Entry [qudt-cat:QUDT-QUANTITY-SchemaCatalogEntry]

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.