In this Technical Specification, the following conventions apply:

  1. Words beginning with a capital letter are either digital representations of real entities or produced in a Virtual Environment.
  2. Words beginning with a small letter have the normal meaning consistent with the relevant context.

In Table 1, a dash “-” preceding a Term means the following:

  1. If the font of the Term is normal, the Term in the table without a dash and preceding the one with a dash should be placed before that Term. The notation is used to concentrate in one place all the Terms that are composed of, e.g., the word Audio followed by one of the words Object, Scene, and Scene Descriptors.
  2. If the font of the Term is italic, the Term in the table without a dash and preceding the one with a dash should be placed after that Term. The notation is used to concentrate in one place all the Terms that are composed of, e.g., the word Attitude preceded by one of the words Social or Spatial.

The full collection of MPAI Term definitions is available online.

Table 1 – Terms and Definitions

Term Definition
Audio Digital representation of an analogue audio signal sampled at a frequency between 8-192 kHz with a number of bits/sample between 8 and 32, and non-linear and linear quantisation. Data with characteristics of Audio may be synthetically produced.
Avatar An Object rendered to represent a Human of a Machine in a virtual space.
–       Model An inanimate Avatar exposing animation interfaces.
–       Portable A Data Type including Avatar ID, Time, Audio-VisualScene Descriptors, Spatial Attitude, Avatar Model, Body Descriptors, Face Descriptors, Language Preference, Speech Coding, Speech Data, Text, and Personal Status [5].
Centre Point The point of an Object selected to have coordinates (0,0,0).
Context Additional information about a communication emitted by an Entity, such as language, culture etc..
Data Information in digital form.
–       Format The standard digital representation of Data.
–       Type An instance of Data with a specific Data Format.
Descriptor The Digital Representation of a feature of an Object.
–       Body A Data Type including the digital representation of the features of the body of a real or digital human.
–       Face A Data Type including the digital representation of a feature of the face of a real or digital human.
Digital Representation Data corresponding to and representing a physical entity.
Environment A Virtual Space that may be null or may include an Audio-Visual Scene.
Human A human being in a real space.
–       Digital A Digitised or a Virtual Human.
–       Digitised An Object that has the appearance of a specific human when rendered.
–       Virtual An Object created by a computer that has a human appearance when rendered but is not a Digitised Human.
Identifier The label uniquely associated with a human or an Object.
Instance An element of a set of entities – Objects, Digital Humans etc. – belonging to some levels in a hierarchical classification (taxonomy).
–       Audio The instance of an Audio Object.
–       Visual The instance of a Visual Object.
Object A data structure that can be rendered to cause an Experience.
–       Audio An Object described by Audio Descriptors.
–       Audio-Visual An Object described by Audio-Visual Descriptors.
–       Body A digital representation of the body of a Human or a Machine.
–       Descriptor The digital representation of the feature of an Object.
–       Digital A Digitised or a Virtual Object.
–       Digitised The digital representation of a real object.
–       Face The digital representation of the face of a Human or a Machine.
–       Speech An Object described by Speech Descriptors.
–       Text A string of Text.
–       Virtual An Object not representing an object in the real environment.
–       Visual An Object described by Visual Descriptors.
Orientation The 3 Euler angles of an Object in a Virtual Space.
Position The coordinates of a representative point for an object in a Virtual Space with respect to a set of coordinate axes.
Rendering The process of instantiating a Virtual Space as a human-perceptible entity.
Scene A composition of Objects located according to a Scene Geometry.
–       Audio A Scene composed of Audio Objects.
–       Digital A digitised scene or a Virtual Scene
–       Audio-Visual A Scene composed of Audio Objects, Visual Objects and co-located Audio-Visual Objects.
–       Visual A Scene composed of Visual Objects.
Scene Descriptors The digital representation of a feature of a scene.
–       Audio A Data Type including the digital representation of the audio features of a digital scene.
–       Audio-Visual A Data Type combining the Audio or Visual Scene Descriptors.
–       Visual A Data Type including the digital representation of the visual features of a digital scene.
Scene Geometry The digital representation of the Object arrangement of a Scene.
–       Audio A Data Type describing the Spatial arrangement of the Visual Objects of a Scene.
–       Audio-Visual A Data Type describing the Spatial arrangement of the Audio, Visual, and Audio-Visual Objects of a Scene.
–       Visual A Data Type describing the Spatial arrangement of the Visual Objects of a Scene.
Attitude
–       Spatial Position and Orientation and their velocities and accelerations of a Human and Visual Object in a Virtual Environment.
Virtual Space A space generated and maintained by a computing platform that can be rendered.
Speech Digital representation of analogue speech sampled at a frequency between 8 kHz and 96 kHz with a number of bits/sample of 8, 16 or 24, and non-linear and linear quantisation or compressed. Data with characteristics of Speech may be synthetically produced.

The Terms used in this standard whose first letter is capital and are not already included in Table 1 are defined in Table 2. To concentrate in one place all the Terms that are composed of a common name followed by other words (e.g., the word Data followed by one of the words Format, Type, or Semantics), the definition given to a Terms preceded by a dash “-” applies to a Term composed by that Term without the dash preceded by the Term that precedes it in the column without a dash.

Table 2 – MPAI-wide Terms

Term Definition
Access Static or slowly changing data that are required by an application such as domain knowledge data, data models, etc.
AI Framework (AIF) The environment where AIWs are executed.
AI Model (AIM) A data processing element receiving AIM-specific Inputs and producing AIM-specific Outputs according to according to its Function. An AIM may be an aggregation of AIMs.
AI Workflow (AIW) A structured aggregation of AIMs implementing a Use Case receiving AIW-specific inputs and producing AIW-specific outputs according to the AIW Function.
Application Standard An MPAI Standard designed to enable a particular application domain.
Channel A connection between an output port of an AIM and an input port of an AIM. The term “connection” is also used as synonymous.
Communication The infrastructure that implements message passing between AIMs.
Component One of the 7 AIF elements: Access, Communication, Controller, Internal Storage, Global Storage, Store, and User Agent
Composite AIM An AIM aggregating more than one AIM.
Component One of the 7 AIF elements: Access, Communication, Controller, Internal Storage, Global Storage, Store, and User Agent
Conformance The attribute of an Implementation of being a correct technical Implem­entation of a Technical Specification.
–       Testing The normative document specifying the Means to Test the Conformance of an Implem­entation.
–       Testing Means Procedures, tools, data sets and/or data set characteristics to Test the Conformance of an Implem­en­tation.
Connection A channel connecting an output port of an AIM and an input port of an AIM.
Controller A Component that manages and controls the AIMs in the AIF, so that they execute in the correct order and at the time when they are needed
Data Information in digital form.
–       Format The standard digital representation of Data.
–       Type An instance of Data with a specific Data Format.
–       Semantics The meaning of Data.
Descriptor Coded representation of a text, audio, speech, or visual feature.
Digital Representation Data corresponding to and representing a physical entity.
Ecosystem The ensemble of actors making it possible for a User to execute an application composed of an AIF, one or more AIWs, each with one or more AIMs potentially sourced from independent implementers.
Explainability The ability to trace the output of an Implementation back to the inputs that have produced it.
Fairness The attribute of an Implementation whose extent of applicability can be assessed by making the training set and/or network open to testing for bias and unanticipated results.
Function The operations effected by an AIW or an AIM on input data.
Global Storage A Component to store data shared by AIMs.
AIM/AIW Storage A Component to store data of the individual AIMs.
Identifier A name that uniquely identifies an Implementation.
Implementation 1.     An embodiment of the MPAI-AIF Technical Specification, or 

2.     An AIW or AIM of a particular Level (1-2-3) conforming with a Use Case of an MPAI Application Standard.
Implementer A legal entity implementing MPAI Technical Specifications.
ImplementerID (IID) A unique name assigned by the ImplementerID Registration Authority to an Implementer.
ImplementerID Registration Authority (IIDRA) The entity appointed by MPAI to assign ImplementerID’s to Implementers.
Instance ID Instance of a class of Objects and the Group of Objects the Instance belongs to.
Interoperability The ability to functionally replace an AIM with another AIW having the same Interoperability Level
–       Level The attribute of an AIW and its AIMs to be executable in an AIF Implementation and to: 

1.     Be proprietary (Level 1)

2.     Pass the Conformance Testing (Level 2) of an Application Standard

3.     Pass the Perform­ance Testing (Level 3) of an Application Standard.
Knowledge Base Structured and/or unstructured information made accessible to AIMs via MPAI-specified interfaces
Message A sequence of Records transported by Communication through Channels.
Normativity The set of attributes of a technology or a set of technologies specified by the applicable parts of an MPAI standard.
Performance The attribute of an Implementation of being Reliable, Robust, Fair and Replicable.
–       Assessment The normative document specifying the Means to Assess the Grade of Performance of an Implementation.
–       Assessment Means Procedures, tools, data sets and/or data set characteristics to Assess the Performance of an Implem­en­tation.
–       Assessor An entity Assessing the Performance of an Implementation.
Profile A particular subset of the technologies used in MPAI-AIF or an AIW of an Application Standard and, where applicable, the classes, other subsets, options and parameters relevant to that subset.
Record A data structure with a specified structure
Reference Model The AIMs and theirs Connections in an AIW.
Reference Software A technically correct software implementation of a Technical Specific­ation containing source code, or source and compiled code.
Reliability The attribute of an Implementation that performs as specified by the Application Standard, profile, and version the Implementation refers to, e.g., within the application scope, stated limitations, and for the period of time specified by the Implementer.
Replicability The attribute of an Implementation whose Performance, as Assessed by a Performance Assessor, can be replicated, within an agreed level, by another Performance Assessor.
Robustness The attribute of an Implementation that copes with data outside of the stated application scope with an estimated degree of confidence.
Scope The domain of applicability of an MPAI Application Standard
Service Provider An entrepreneur who offers an Implementation as a service (e.g., a recommendation service) to Users.
Standard A set of Technical Specification, Reference Software, Conformance Testing, Performance Assessment, and Technical Report of an MPAI application Standard.
Technical Specification (Framework) the normative specification of the AIF. 

(Application) the normative specification of the set of AIWs belon­ging to an application domain along with the AIMs required to Im­plem­ent the AIWs that includes:

1.     The formats of the Input/Output data of the AIWs implementing the AIWs.

2.     The Connections of the AIMs of the AIW.

3.     The formats of the Input/Output data of the AIMs belonging to the AIW.
Testing Laboratory A laboratory accredited to Assess the Grade of  Performance of Implementations.
Time Base The protocol specifying how Components can access timing information
Topology The set of AIM Connections of an AIW.
Use Case A particular instance of the Application domain target of an Application Standard.
User A user of an Implementation.
User Agent The Component interfacing the user with an AIF through the Controller
Version A revision or extension of a Standard or of one of its elements.
Zero Trust A cybersecurity model primarily focused on data and service protection that assumes no implicit trust.