Information Model Specification - The Information Model is used as the source for class, attribute, and data type definitions. The model is presented in document format as the Information Model Specification.

ISO/IEC 11179:3 Registry Metamodel and Basic Attributes Specification, 2003. - The ISO/IEC 11179 specification provides the schema for the data dictionary.

Planetary Science Data Dictionary - The online version of the PDS3 data dictionary was used as the source for a few data elements being carried over from the PDS3 data standards.

An attribute is a property or characteristic that provides a unit of information. For example, 'color' and 'length' are possible attributes.

A class is a set of attributes (including a name) which defines a family. A class is generic - a template from which individual members of the family may be constructed.

A conceptual object is an object which is intangible (and, because it is intangible, does not fit into a digital archive). Examples of 'conceptual objects' include the Cassini mission and NASA's strategic plan for solar system exploration. Note that a PDF describing the Cassini mission is a digital object, not a conceptual object (nor a component of a conceptual object).

A data element is a unit of data for which the definition, identification, representation and permissible values are specified by means of a set of attributes. For example, the concept of a calibration_lamp_state_flag is used to indicate whether the lamp used for onboard camera calibration was turned on or off during the capture of an image. The data element aspect of this concept is the named attribute (or data element) calibration_lamp_state_flag.

A data object is a physical, conceptual, or digital object.

A digital object is an object which is real data - for example, a binary image of a redwood tree or an ASCII table of atmospheric composition versus altitude.

Formal as used in the definition of attributes that are names indicates that an established procedure was involved in creating the name.

A unique identifier is a special type of identifier used to provide a reference number which is unique in a context.

Local refers to the context within a single label.

Logical as used in the definition of logical identifier indicates that the identifier logically groups a set of objects.

A physical object is an object which is physical or tangible (and, therefore, does not itself fit into a digital archive). Examples of 'physical objects' include the planet Saturn and the Venus Express magnetometer. Note that an ASCII file describing Saturn is a digital object, not a physical object (nor a component of a physical object).

A resource is the target (referent) of any Uniform Resource Identifier; the thing to which a URI points.