This is a snapshot of the specification that was created during midPrivacy: provenance prototype project. For the latest development version of the document please look in Axiom workspace.

The following terms are used in Axiom:


Axiom model defines set of type, item, value and metadata definitions. Model is a basic "packaging" mechanism for Axiom definitions.


Set of one or several models that are used together. Schema is usually set of models that are loaded and active in an application. Schema is a "soft" concept, it is not formally defined anywhere in Axiom definitions.


Data item which can have one or more values. It is identified by item name.

item name

Name of data item. Item name can be local (if item is native to the data type) or fully qualified name (if item is external/ augmented to the data type).


Represents a type of value. It can be simple type or structured type, and may its instance (value) may have value metadata attached.

simple type

A type, which has simple value (eg. integer, string), does not have nested items.

structured type

A type, which has structured value - value consisting of multiple named items.


Represents concrete instance of type. The value is instance of type and may have value metadata attached.


Data about data. Metadata may describe origin of the data, trustworthiness and so on.

value metadata

Represents metadata attached to value. Each individual value of an item may have different metadata.


Mechanism for declaring additional items to already defined objects.

representation format

(also serialization format) Specific data format used to store the data. JSON, XML and YAML are examples of representation formats.